How Accurate is the Apple Watch as a Fitness Tracker?

One of the key features of the Apple Watch is its ability to serve as a fitness tracker, replacing devices made by Fitbit, Nike, Jawbone, and others. Fitness trackers are often quite inaccurate; I’ve tested several, and only the Fitbit One counts steps accurately. Some fitness trackers also have heart rate sensors, as the Apple Watch does, but I’ve never tested any of those.

But how about the Apple Watch? Is it accurate?

I’ve had my Apple Watch for three days, and I’ve been recording my activity, and comparing it to the Fitbit One. I’ve found that, in some ways, the Apple Watch is very accurate; in others, it’s all over the place.

The Apple Watch records different types of metrics, not just steps. While it does keep a step count, it focuses on three metrics to determine your activity. You can see them in the three rings that display on the Apple Watch, and in the Activity app on an iPhone:

Activity rings

The outer ring shows the number of active calories you have expended, and the ring is based on a goal you set (I set mine to 500 calories, and increased it after the Watch prompted me to on Sunday evening). The second ring is active minutes; it is measured against a goal of 30 minutes a day. The third ring is standing time: it measures whether you have stood for at least one minute in each of twelve hours of the day. As you can see, all my rings were will beyond their goals yesterday. When you reach a goal, the end of the ring is at 12 o’clock; as you exceed your goals, the ring keeps turning.

The Activity app also shows you more detail: the number of calories, number of active minutes, workouts (if you’ve used the Workout app on the Apple Watch), and the number of steps you’ve taken, and their distance. It’s this final metric that allows one to compare the Apple Watch with other devices.

Counting Steps

Since I’ve had the Apple Watch, I’ve also been wearing my Fitbit One. On Saturday, the Apple Watch recorded 8,300 steps, and the Fitbit counted 8,480. On Sunday, the Apple Watch counted 7,938 steps, and the Fitbit 8,409. In my tests, fitness trackers that you wear on your wrist are very inaccurate, and all the devices I tested over-counted steps. The Apple Watch, however, is under-counting. The Saturday number was very close, but Sunday’s number was about 5% less. I suspect that the Apple Watch is comparing movement data with what is recorded by the iPhone’s motion co-processor, allowing it to be more accurate than standard wrist-worn devices, but it will never be as accurate as counting steps as a pedometer that you wear on your belt (such as the Fitbit One).

But Apple doesn’t use steps as the main metric; I think the only reason they show the step count is because people are used to seeing this number with a fitness tracker (with the notable exception of the defunct Nike+ Fuelband). Apple is focusing on calories, and that’s the main goal you set.

Counting Calories

Apple and Fitbit clearly use different calculations for calories. The Apple Watch has the advantage of being able to check your heart rate (the only Fitbit device that can do this is the Fitbit Surge). It checks your heart rate every 10 minutes, or more or less continuously when you perform a workout using the Workout app on the watch (unless you’ve put the Workout app in Power Saving Mode, in the settings). But how accurate is the Apple Watch’s heart rate sensor? For the most part, when I check it, the numbers look good. But, at times, it’s way off.

When walking on my treadmill yesterday, I checked my heart rate in the Workout glance on my Apple Watch. At times, it was around 100, which seemed to be correct. But several times, it was very low, such as 64 or 72. At one point, I took my heart rate with Withings’ HealthMate app, which lets you measure your pulse by placing your finger over the camera lens of the iPhone. At the left, the Apple Watch; at the right, the Withings HealthMate app:


Apple watch heart rate   Withings heart rate

Also, one time when I was walking outdoors, I checked my heart rate on the Apple Watch, and it said 153. I took my pulse just in case, but it wasn’t that high, it was around 110. The Apple Watch got the number right a couple of minutes later.

With this in mind, I looked at the calorie calculations for both the Apple Watch and the Fitbit. On Saturday, the Apple Watch credited me with 687 active calories and 3,180 resting calories, for a total of 3,867. The Fitbit app calculated that I burned 2,742 calories. On Sunday, the Apple Watch counted a total of 3,915 calories, compared to 2,752 for the Fitbit app.

I’m not sure how these numbers can be so widely divergent. I tend to think the Fitbit app is more realistic (neither can be accurate, since measuring calories is a bit of black magic). Calorie calculators for my age, sex, and weight, show numbers closer to those of Fitbit.

Counting Active Minutes

Another metric that the Apple Watch counts is active minutes. As Apple says, the Exercise ring:

“displays how many minutes of brisk activity you’ve completed towards a goal of 30 minutes. Every minute of movement that equals or exceeds a brisk walk, whether it’s working out or playing with your kids, counts toward your Exercise goal.”

As such, any brisk walking should count as active minutes. In my tests, I found that I could take a walk at a steady pace, and some of its minutes would count, others not. For example, yesterday evening, I walked outside for 21 minutes, with my heart rate around 105. I was warm, nearly sweating, so I think this counts as brisk. The first 5 minutes were clocked as active, but the rest of the walk wasn’t. If I walk on my treadmill, some of the minutes count, and most don’t.

Apple says that you should calibrate your Apple Watch, for better accuracy. This isn’t complicated: just walk or run outdoors with your iPhone for 20 minutes or more, and the Apple Watch should calibrate using the GPS to determine how long your stride is at different speeds. I’ve done this, twice.

A number of users have chimed in on a long thread on Apple’s support forum. Some people suggest that active minutes depend on your heart rate, that it should be in the aerobic level; that’s not what Apple says. Brisk activity is not aerobic. It’s clear that some activities will pose problems to the Apple Watch. Since it can use GPS to track you, it can determine your pace, and how much distance you cover, when you’re walking or running outdoors. But for indoor activity, such as a treadmill, it can only use the speed of your steps and your heart rate. So, while it will calculate calories for such activities, it won’t calculate active minutes. (Though you can override this with the Workout app by recording your activity as an Other workout. All its minutes will count.)

In addition, I’ve been watching when it records active minutes. Yesterday, for example, it recorded a few active minutes in a supermarket. I wasn’t excited enough about the tomatoes I bought – even though they were very good – to make my heart race for several minutes, yet the Apple Watch counted some of that time as active. Just as it did when I was watering the lawn on Saturday.

The Fitbit records active minutes, presumably just based on pace, since it has no other sensors. On Saturday, it recorded 47 active minutes, and on Sunday, 33. The Apple Watch recorded 31 minutes on Saturday, and 50 on Sunday, but that’s with my using the Workouts app to “force” it to record my minutes on the treadmill, so I can’t really compare which is more accurate.

In a walk I took today on my treadmill, using the Indoor Walk workout, for thirty minutes of activity, only 5 were counted as active. Here’s what my Exercise ring looks like after the walk (I don’t know what I was doing earlier today to get one minute of activity):


IMG 2935  IMG 2934

Since I was walking at a constant pace, with a heart rate that was roughly constant after the first couple of minutes, why didn’t more than six minutes count as exercise? Could it be that the heart rate sensor, which clearly has some issues, meant that it was only accurately recording my heart rate for a few minutes?

If I look at the Health app, it shows several readings per minute for my heart rate. If you look here at 12:44, you can see that it’s clearly not getting it right. It’s worth noting that I’m wearing the watch snugly, so much so that I can’t fit a finger between my band and my wrist, but it’s not too tight either.

Heart rate

There’s also another, longer period, from 12:52 to 12:54, where my recorded heart rate dropped from 100 to 87, then, at 12:55, it went up to 108. It stayed from around 103 to 108 for the remainder of the walk, which ended at 1:00.

Tracking Distance

The Apple Watch also seems to have difficulty recording distance and pace for an indoor workout. This shouldn’t be hard. The Apple Watch knows the approximate length of my stride, especially since I calibrated it outdoors with GPS. So it should calculate distance and pace based on the number of steps I take, multiplied by my stride. In a half-hour walk today, it recorded a distance of 1.5 km, whereas my treadmill recorded 1.7 miles (about 2.7 km). While I was walking, I checked the pace, and it was all over the map, ranging from 20 min/km to just over 9 min/km. I was walking at 3.6 mph, so the actual pace should have been around 10:20 per km. Sometimes the Apple Watch lost track of my pace entirely. I took a number of screenshots while walking; they’re in time order, as you can see in the upper-right corner of each image. (I started my workout around 12:30, and only started looking at the Workouts app after about 20 minutes of walking.)

IMG 2920  IMG 2921  IMG 2923  IMG 2925  IMG 2926  IMG 2928

At the time of this writing, after I walked on my treadmill for a half hour, the Apple Watch shows that I have walked 1.58 miles, and the Health app, where I am able to change the units, shows a total of 2.56 km. The Fitbit app, which simply calculates steps multiplied by stride (based on a stride I measured), says I walked 3.22 km, which matches more correctly with what my treadmill showed. The step count is nearly the same: 3,524 on the Apple Watch, and 3,575 for the Fitbit.

I’ve said before that fitness trackers are more about motivation than accuracy. If they get you to be more active, by prodding you to reach new goals, then they are successful. They should give you reliable data about your activity, though, and not be far off the mark. (I consider that the 5% difference in step count is acceptable.) But they shouldn’t lead you to wonder whether your activity is counted correctly, as the Apple Watch does. Either the Apple Watch is severely flawed in its fitness tracking capabilities, or I received a dud (I’m going to call Apple later to try and find out). I’m curious as to whether other readers have compared the Apple Watch with other fitness trackers, or whether anyone has similar data, reported by the Apple Watch, which just seems wrong. Feel free to post in the comments if you do.

130 thoughts on “How Accurate is the Apple Watch as a Fitness Tracker?

  1. Hello, great article! Question for the folks that report that the Apple Watch takes a heart rate reading every 10 or 30 minutes – is that observed or stated? Reason I ask is that when I check my Health app, the frequency/interval of the HR readings seems extremely spotty and random. Sometimes it seems like it might be every 20 minutes, other times it appears to go over an hour without taking a reading.

    However, it does appear that when I’ve let it know I’m IN a workout (via the Workout app), it then takes 2-3 readings per minute. Better than the random-interval readings throughout the day, but probably still nowhere near the same number of readings my chest strap unit is taking. I get that the Apple Watch tires easily and has to be frugal about when it does these things, but a reliable interval would be nice.

    Comparing the calories burned between Apple’s Workout app and the DigitFit app (paired with a Polar chest strap unit) for a strength workout, the Apple Workout app reported almost 100 fewer calories burned than the DigiFit app. The Workout app also reported a slightly lower average HR than the DigiFit app/Polar chest strap) did. Also, to obtain max/min heart rates achieved during the workout, I needed to scroll through the many readings in the Health app on the iPhone – as opposed to just having the min/max HR (and a few other handy data points) listed in the DigiFit

    At this early stage (Day 2 with the Apple Watch), I’m with some of the other reviewers in that I’ll stick with a dedicated bluetooth chest strap and DigiFit app for my information needs.

    • In another article, I explain that Apple changed the way the Apple Watch records your heartbeat. It checks every 10 minutes, but not if you’re moving. Apple had to change because the readings were so unreliable. If you are doing a workout, though, then it checks pretty much constantly, but I find the readings still vary greatly.As for calories, it’s been better since the release of WatchOS 2 – resting calories are not as ridiculous – but it will always differ from the numbers that other devices give.

      • Thanks, Kirk. I’d be interested in that article if you have the link to it handy.

        When you say it checks every 10 min, but not if you’re moving – does that mean that if you happen to be moving (say, walking and swinging your arms) when the 10 minute measurement interval comes up, it skips that measurement and tries again in 10 minutes? And it will keep doing that until it finds that you are motionless for an accurate reading?

        Thanks for the clarification!

  2. Hello, great article! Question for the folks that report that the Apple Watch takes a heart rate reading every 10 or 30 minutes – is that observed or stated? Reason I ask is that when I check my Health app, the frequency/interval of the HR readings seems extremely spotty and random. Sometimes it seems like it might be every 20 minutes, other times it appears to go over an hour without taking a reading.

    However, it does appear that when I’ve let it know I’m IN a workout (via the Workout app), it then takes 2-3 readings per minute. Better than the random-interval readings throughout the day, but probably still nowhere near the same number of readings my chest strap unit is taking. I get that the Apple Watch tires easily and has to be frugal about when it does these things, but a reliable interval would be nice.

    Comparing the calories burned between Apple’s Workout app and the DigitFit app (paired with a Polar chest strap unit) for a strength workout, the Apple Workout app reported almost 100 fewer calories burned than the DigiFit app. The Workout app also reported a slightly lower average HR than the DigiFit app/Polar chest strap) did. Also, to obtain max/min heart rates achieved during the workout, I needed to scroll through the many readings in the Health app on the iPhone – as opposed to just having the min/max HR (and a few other handy data points) listed in the DigiFit

    At this early stage (Day 2 with the Apple Watch), I’m with some of the other reviewers in that I’ll stick with a dedicated bluetooth chest strap and DigiFit app for my information needs.

    • In another article, I explain that Apple changed the way the Apple Watch records your heartbeat. It checks every 10 minutes, but not if you’re moving. Apple had to change because the readings were so unreliable. If you are doing a workout, though, then it checks pretty much constantly, but I find the readings still vary greatly.As for calories, it’s been better since the release of WatchOS 2 – resting calories are not as ridiculous – but it will always differ from the numbers that other devices give.

      • Thanks, Kirk. I’d be interested in that article if you have the link to it handy.

        When you say it checks every 10 min, but not if you’re moving – does that mean that if you happen to be moving (say, walking and swinging your arms) when the 10 minute measurement interval comes up, it skips that measurement and tries again in 10 minutes? And it will keep doing that until it finds that you are motionless for an accurate reading?

        Thanks for the clarification!

  3. 12-7-2015
    This morning I rode my lemond spin bike at home (indoors, of course) for 50 minutes with my new Apple Watch and a chest strap connected to the lemond pilot device on the spin bike. Apple Watch says I burned 295 calories. Chest strap and pilot say I burned 484 calories. That’s nearly a 200-calori difference! When I entered the indoor bike ride into the My Fitness Pal app, it estimated that I burned 484 as well (usually, MFP calculates the calorie burn at just slightly less than the chest strap and pilot). This seems to indicate that the Apple Watch is calculating the calorie burn too low for the indoor bike. This is dismaying, given the cost of the device.

    I hope apple folks are aware of this discussion resource. I will try the “Other” setting and see if it calculates the calorie burn differently. Very glad this site and discussion exists. Thanks.
    -Cassie

    • On 12-9-2015, I tried the Other setting on my Apple Watch, sub-set for the open-ended workout, for my ride on my lemond spin bike. No difference from the Apple Watch indoor cycling setting as far as the calorie calculation was concerned.
      Next, I tried using the Other/Open-ended setting to see how the watch tracked my heart rate, which it should be doing constantly when using the workout feature. It showed an accurate heart rate and, just as often, a clearly-wrong heart rate — much too high or much too low, or “measuring” (aka no reading). I’m dismayed at the watch’s poor performance in this feature. And my watch band was as tight as possible. Sigh. Any suggestions would be appreciated. Thanks again for the forum.

  4. 12-7-2015
    This morning I rode my lemond spin bike at home (indoors, of course) for 50 minutes with my new Apple Watch and a chest strap connected to the lemond pilot device on the spin bike. Apple Watch says I burned 295 calories. Chest strap and pilot say I burned 484 calories. That’s nearly a 200-calori difference! When I entered the indoor bike ride into the My Fitness Pal app, it estimated that I burned 484 as well (usually, MFP calculates the calorie burn at just slightly less than the chest strap and pilot). This seems to indicate that the Apple Watch is calculating the calorie burn too low for the indoor bike. This is dismaying, given the cost of the device.

    I hope apple folks are aware of this discussion resource. I will try the “Other” setting and see if it calculates the calorie burn differently. Very glad this site and discussion exists. Thanks.
    -Cassie

    • On 12-9-2015, I tried the Other setting on my Apple Watch, sub-set for the open-ended workout, for my ride on my lemond spin bike. No difference from the Apple Watch indoor cycling setting as far as the calorie calculation was concerned.
      Next, I tried using the Other/Open-ended setting to see how the watch tracked my heart rate, which it should be doing constantly when using the workout feature. It showed an accurate heart rate and, just as often, a clearly-wrong heart rate — much too high or much too low, or “measuring” (aka no reading). I’m dismayed at the watch’s poor performance in this feature. And my watch band was as tight as possible. Sigh. Any suggestions would be appreciated. Thanks again for the forum.

  5. I just got my Apple Watch a month ago. Those three rings were driving me crazy trying to figure out the logic behind them and how to change the settings for each. So I was online looking for more details about how the activity and workout modes work, when I came across your post.

    Some of your post is over my head, but you look like you are doing a very thorough job of checking into the accuracy of the watch and the best ways to record activity, so I’ll keep watching your posts in an effort to learn how all this works.

    I use the Lose It app to count calories so I’m especially interested in how the Health Kit Workout and Steps sync over and effect my ratio of ‘calories burned to calories eaten’ on my Lose It app.

  6. I just got my Apple Watch a month ago. Those three rings were driving me crazy trying to figure out the logic behind them and how to change the settings for each. So I was online looking for more details about how the activity and workout modes work, when I came across your post.

    Some of your post is over my head, but you look like you are doing a very thorough job of checking into the accuracy of the watch and the best ways to record activity, so I’ll keep watching your posts in an effort to learn how all this works.

    I use the Lose It app to count calories so I’m especially interested in how the Health Kit Workout and Steps sync over and effect my ratio of ‘calories burned to calories eaten’ on my Lose It app.

  7. So frustrated – just got the apple watch and wore it to my regular workout – a vigorous kettle bell class – and it recorded me as working out for 7 minutes.
    If I can’t figure out a way to get a more accurate read, I may not keep the watch…. searching for a solution.

  8. So frustrated – just got the apple watch and wore it to my regular workout – a vigorous kettle bell class – and it recorded me as working out for 7 minutes.
    If I can’t figure out a way to get a more accurate read, I may not keep the watch…. searching for a solution.

  9. My husband and I both have the iWatch and we walked around the city yesterday and I registered as doing less km’s than him! We went exactly to the same place. I know maybe he made more steps but not as much as what was recorded. I am still trying to figure out if the iWatch is accurate.

  10. My husband and I both have the iWatch and we walked around the city yesterday and I registered as doing less km’s than him! We went exactly to the same place. I know maybe he made more steps but not as much as what was recorded. I am still trying to figure out if the iWatch is accurate.

  11. It’s been about 8 months since the original post. I’d be curious to know what Apple’s response was? I’ve had my watch for a month. Only got it for the fitness tracking and it’s completely inaccurate. I say this as I wear my Polar Heart Rate monitor when working out and the steps, calories, distance and minutes differ from watch. Very frustrating. Thankfully I meet all my goals so don’t pay for that watch but if I did it would completely not be worth it

  12. It’s been about 8 months since the original post. I’d be curious to know what Apple’s response was? I’ve had my watch for a month. Only got it for the fitness tracking and it’s completely inaccurate. I say this as I wear my Polar Heart Rate monitor when working out and the steps, calories, distance and minutes differ from watch. Very frustrating. Thankfully I meet all my goals so don’t pay for that watch but if I did it would completely not be worth it

  13. I have just closed 4 cases with Apple genius tech support. Spent more than 5-6 hours with different Geniuses and finally my call my was escalated to T2 tech support and now I am talking to real engineers.
    Simply apple watch cannot track your indoor or outdoor walking properly. I am not talking about accuracy in distance or accuracy as in steps. Very simply, I am talking about how many minutes I have walked (outdoors) today and how many minutes it reports at the end of the day in total exercise minutes. Well good luck! I have taken screenshots, recordings comparison etc just to prove them that it is really buggy and not wort wearing this if you are trying to keep yourself active and motivated because you cannot.
    I have sowed them that I have completed 45mins of brisk walk outdoors and the green exercise circle only reports 2mins of it.
    Another day I have walked over 1hr and only 17mins were reported.
    My average pace is 20:00 min/mile which is something like 2.8 2.9 mile per hour. But of course it changes, sometimes I am walking up a hill or slow the tempo down for 2-3mins and try to keep it up to fast pace again. Like any other walking exercise.
    Well, the explanation was very funny. Apparently apple watch doesn’t count these walking sessions as exercise because sometimes I slow down and my speed is under 3mhp. I started laughing because their explanation was “Yes sir but technically outdoor walking is more than 3mph so it doesn’t count”
    I couldn’t really believe this logic and asked them “Ok so what is all that 128 avg heart beat during this whole 45mins of time and the GPS recording which obviously proves that I ‘ve been walking and sweating like p*g and watch doesn’t like what I did?”
    They couldn’t say anything and kept saying same thing which I should walking at least 3mph avg during the whole outdoor walking ;).

    I have reported this to Apple but I don’t know if they fix this issue or not.
    I am an 43 yrs old man with disability and just trying to be healthy . That’s why it is really important for me to track these thing down because it motivates but looks like Apple doesn’t like 43 year old man with disability trying to walk 😉

  14. I have just closed 4 cases with Apple genius tech support. Spent more than 5-6 hours with different Geniuses and finally my call my was escalated to T2 tech support and now I am talking to real engineers.
    Simply apple watch cannot track your indoor or outdoor walking properly. I am not talking about accuracy in distance or accuracy as in steps. Very simply, I am talking about how many minutes I have walked (outdoors) today and how many minutes it reports at the end of the day in total exercise minutes. Well good luck! I have taken screenshots, recordings comparison etc just to prove them that it is really buggy and not wort wearing this if you are trying to keep yourself active and motivated because you cannot.
    I have sowed them that I have completed 45mins of brisk walk outdoors and the green exercise circle only reports 2mins of it.
    Another day I have walked over 1hr and only 17mins were reported.
    My average pace is 20:00 min/mile which is something like 2.8 2.9 mile per hour. But of course it changes, sometimes I am walking up a hill or slow the tempo down for 2-3mins and try to keep it up to fast pace again. Like any other walking exercise.
    Well, the explanation was very funny. Apparently apple watch doesn’t count these walking sessions as exercise because sometimes I slow down and my speed is under 3mhp. I started laughing because their explanation was “Yes sir but technically outdoor walking is more than 3mph so it doesn’t count”
    I couldn’t really believe this logic and asked them “Ok so what is all that 128 avg heart beat during this whole 45mins of time and the GPS recording which obviously proves that I ‘ve been walking and sweating like p*g and watch doesn’t like what I did?”
    They couldn’t say anything and kept saying same thing which I should walking at least 3mph avg during the whole outdoor walking ;).

    I have reported this to Apple but I don’t know if they fix this issue or not.
    I am an 43 yrs old man with disability and just trying to be healthy . That’s why it is really important for me to track these thing down because it motivates but looks like Apple doesn’t like 43 year old man with disability trying to walk 😉

  15. Has anyone found a good app for the Apple watch that will add workouts or calories burned when not wearing the watch? eg. adding in a swim workout or weights at the gym?

    When cross training which method of recording the workout is most accurate?

    I have not seen it explicitly stated but I have assumed that the height, weight and other information entered when setting up the watch is taken into account when using the workout functions?

    Thanks! 🙂

  16. Has anyone found a good app for the Apple watch that will add workouts or calories burned when not wearing the watch? eg. adding in a swim workout or weights at the gym?

    When cross training which method of recording the workout is most accurate?

    I have not seen it explicitly stated but I have assumed that the height, weight and other information entered when setting up the watch is taken into account when using the workout functions?

    Thanks! 🙂

  17. I really enjoyed this article. Well done!! Strangely. I’ve had the opposite experience with my Apple Watch 3 (compared to other devices), I found that the AW3 consistently underestimates my calorie burn but I guess I’d prefer this than the opposite scenario.

    The brisk walking not consistently counting as exercise doesn’t really bother me, as I don’t really consider it exercise either.

    The only disappointment is that I feel like it AW3 really does underestimate my squash burn. I will play a hard competitive game of squash for 45min (average heat rate of 130+) and it will say I only burned 300 calories. My FitBit would track a similar workout at almost 700. Oh well – Otherwise I am thrilled with the watch. Love the HRR and HRV features.

  18. I really enjoyed this article. Well done!! Strangely. I’ve had the opposite experience with my Apple Watch 3 (compared to other devices), I found that the AW3 consistently underestimates my calorie burn but I guess I’d prefer this than the opposite scenario.

    The brisk walking not consistently counting as exercise doesn’t really bother me, as I don’t really consider it exercise either.

    The only disappointment is that I feel like it AW3 really does underestimate my squash burn. I will play a hard competitive game of squash for 45min (average heat rate of 130+) and it will say I only burned 300 calories. My FitBit would track a similar workout at almost 700. Oh well – Otherwise I am thrilled with the watch. Love the HRR and HRV features.

  19. Thanks for writing this.

    My experience is very different. I tried 2 different fitbits, gained weight on both, and a Garmin, which was ok, but I didn’t like wearing a chest strap.

    I will say, there’s way more to it than your heart beat. That’s only one indication of your activity. But, I find Apple Watch to be incredibly accurate. For a while, I worked out with my Apple Watch on. And, on a calorie restriction, I ate back the exercise calories the watch recorded and I lost weight. This was on a 500/day calorie restriction. So, nothing crazy. Accuracy has to be there for only 500 less per day. And it worked really well.

    Also, it’s true that over time, it learns. So, it can take some time to dial things in. It took months before I felt I was getting accurate data from my activities.

    I don’t eat back exercise calories at the moment, so the calorie burn is a simple indicator for me.

  20. Thanks for writing this.

    My experience is very different. I tried 2 different fitbits, gained weight on both, and a Garmin, which was ok, but I didn’t like wearing a chest strap.

    I will say, there’s way more to it than your heart beat. That’s only one indication of your activity. But, I find Apple Watch to be incredibly accurate. For a while, I worked out with my Apple Watch on. And, on a calorie restriction, I ate back the exercise calories the watch recorded and I lost weight. This was on a 500/day calorie restriction. So, nothing crazy. Accuracy has to be there for only 500 less per day. And it worked really well.

    Also, it’s true that over time, it learns. So, it can take some time to dial things in. It took months before I felt I was getting accurate data from my activities.

    I don’t eat back exercise calories at the moment, so the calorie burn is a simple indicator for me.

  21. My wife and I both have Apple Watches and when we go for walks together I always get more ‘exercise’ minutes even though my heart rate is much lower than hers. Usually about 2 to 3 times as much! Estimated calories are about the same. We’ve both tried recalibrating but that has made no difference.

  22. My wife and I both have Apple Watches and when we go for walks together I always get more ‘exercise’ minutes even though my heart rate is much lower than hers. Usually about 2 to 3 times as much! Estimated calories are about the same. We’ve both tried recalibrating but that has made no difference.

  23. Thanks for writing this! Any new discoveries? I’m having the exact same issue with my apple watch and wish it would be more accurate for indoor activity!

    • No, I haven’t looked into it since the early days. I don’t think it’s any more accurate; there’s no accurate way to count calories anyway (other than locking someone in a special room and analyzing how much CO2 they exhale), so it can never be any more than a guess. Though the resting calories thing should be easier to estimate.

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