Is Apple Watch Accurate on Treadmill? Distance, Pace and Calibration Explained

If you have ever wondered, “Is Apple Watch accurate on treadmill workouts?”, you are not alone, especially when the distance displayed on the treadmill does not match what your watch shows after an indoor run. I noticed that problem when my Apple Watch was constantly displaying smaller distances than the treadmill display.

The simple answer is yes, the Apple Watch can be quite accurate on the treadmill, although after calibration, indoor exercises are generally less accurate than GPS workouts because your watch calculates distances based on stride length, arm movements and accelerometer data.

Finally, after trying different calibration options and going outside for a couple of walks and runs, I managed to make my Apple Watch distance very close to the treadmill distance.

Quick Answer: Is Apple Watch Accurate on Treadmill?

Apple Watch will give an accurate enough measurement for treadmill trends after calibration. But since the Apple Watch uses stride and arm movement to gauge the indoor distance and not GPS, there will likely be differences between the measured pace and distance.

A calibrated treadmill or one that is connected to GymKit will display an accurate result for distance. Apple Watch is more accurate for heart rate and calorie measurements.

Why Apple Watch Does Not Match the Treadmill

GPS Does Not Help Indoors

Apple Watch, like most smartwatches, relies upon GPS, accelerometer and heart rate sensor for an outside walk or run. And because of GPS, the distance and steps are fairly accurate most of the time with minimal disparity. 

However, at an indoor run or walk on a treadmill, GPS is rendered mostly useless because you’re moving in the same place. That is why Apple Watch treadmill accuracy often feels worse indoors compared to outdoor runs.

Apple Watch Estimates Distance From Stride and Arm Movement

So your Apple Watch relies upon your movement tracked by an accelerometer and along with your stride length, arm swing, pace, and other workout data to estimate distance indoors. Since there’s no location tracker (GPS), there is a difference between the treadmill distance and the Apple Watch distance. And it is massive. Many users have found that the more they walk or run indoors, the greater the difference. It is terrible, to say the least, but what can you do about it? Well, here’s what I suggest. 

Calibrate your data manually. Which is basically telling your Apple Watch about your stride, your natural pace of running and walking and simply getting the watch to accurately measure your workouts without GPS. 

Even if you don’t calibrate your data, your Apple Watch learns about your pace and stride over time, but this can take time and has a scope of inaccuracy. That’s why manually calibrating makes more sense here. 

Also, before we begin with the steps, just verify whether the personal data you’ve added to your Apple Watch app and otherwise is accurate or not. Your body weight, height, age and everything need to be correct. If there’s a change in something, your workout data will have more inaccuracies. 

Holding Treadmill Handles Can Reduce Accuracy

When holding onto the treadmill railings as you walk or jog, you do not provide enough arm movements, thereby affecting the distance calculation of your Apple Watch quite significantly.

The problem is particularly evident when using an incline walk or a treadmill at low speeds and most people grab the rails for support. Allowing your watch arm to swing freely generally works better indoors.

Incline and Speed Changes Affect Accuracy

Indoor treadmill workouts with incline angle and speed can influence distance estimation on Apple Watch because of changing stride lengths.

Your steps when walking uphill are very different from jogging on a flat treadmill surface. As a result, the Apple Watch is likely to misestimate the distance if the speeds change often.

Your Treadmill May Also Be Inaccurate

The treadmill is not always accurate, particularly if the equipment is old or not well-maintained. In most cases, both the treadmill and the Apple Watch provide an estimated distance based on their own calculations.

For this reason, even with calibration, the numbers will never match up to perfection. The key thing is consistency, not absolute accuracy.

Apple Watch vs Treadmill: Which Distance Should You Trust?

In most treadmill workouts, the treadmill itself tends to provide more accurate data on pace and distance compared to the Apple Watch, which performs better when it comes to recording your heart rate.

Which Apple Watch Metrics Are Accurate on a Treadmill?

Distance Accuracy

Apple Watch treadmill distance inaccurate is a common problem. The accuracy is decent after calibration, but it is still likely to be less accurate than outdoor GPS runs. As the watch uses stride length and arm swings for measuring distances in an indoor environment, there may be slight differences between the treadmill and Apple Watch measurements.

Regular calibration of the watch outdoors would help achieve better results indoors while running and walking.

Pace Accuracy

Pace accuracy while using a treadmill mostly relies on distance estimation. If the watch over or underestimates the distance that was measured, the corresponding pace readings will also seem off.

For exact pace measurements on a treadmill, you are likely to be better off trusting the treadmill itself.

Heart Rate Accuracy

Apple Watch is normally very accurate when it comes to heart rate tracking during treadmill exercises. However, there are a few instances where the watch fails to track heart rate accurately.

The fit of the Apple Watch is crucial when it comes to heart rate monitoring during workouts. For instance, a loose band, tattoos, cold hands, heavy sweating,and lots of wrist motions will result in inaccurate heart rate measurements.

Calories Burned Accuracy

The Apple Watch is quite effective in estimating calories burned during a workout session. The estimation is done using the user’s heart rate, movement, age, weight, height and sex.

Incorrect details in the Health app might lead to inaccurate calorie burn estimations.

Steps Accuracy

Step count estimation on the treadmill largely depends on the movements of the hands. Holding onto the bars for extended periods or keeping your watch hand still can lead to fewer counts and distances covered.

Swinging hands freely works best while walking or running on a treadmill.

Turn On Motion Calibration & Distance in Settings

1. Launch the Settings app on your iPhone and go to Privacy & Security.
2. Go to Location Services and ensure that the location is turned on. 

1. Scroll a bit and click on System Services. 
2. Now, turn on Motion Calibration & Distance.

Settings > Privacy & Security > Location Services > System Services > Motion Calibration & Distance

Reset Your Previous Calibration Data 

1. Now, open the Watch app on your iPhone. 
2. Go to the My Watch tab and click on Privacy.
3. Hit Reset Fitness Calibration Data at the bottom. 

Watch app > Privacy > Reset Fitness Calibration Data

Calibrate Your Apple Watch 

To calibrate Apple Watch for treadmill properly, you need to do an Outdoor run or walk. It cannot be an indoor workout. Your watch detects most accurately with GPS and that’s how it will best learn about your pace. After you have calibrated, you can do an indoor walk or run on a treadmill. 

1. Be in an outdoor area with good GPS reception and clear skies. 
2. Launch the Workout app on your Apple Watch. 
3. Select Outdoor Walk or Outdoor Run, or whatever you feel like doing. 
4. Walk or run at your natural pace for around 20 minutes. 

Repeat the calibration process several times if you have different walking or running paces. Every time you run or walk outdoors, the Apple Watch calibrates the accelerometer by learning your stride at different speeds. 

Apple suggests walking or jogging outdoors for about 20 minutes in an open space where the GPS signal strength is good to help the watch understand your stride length in various speeds.

How GymKit or “Connects to Apple Watch” Improves Accuracy

Provided your treadmill has either GymKit or the “Connects to Apple Watch” symbol, then it is possible to link it to your Apple Watch in order to get a more accurate indoor workout experience.

This means that the information will be transferred from both devices, which will help you get more accurate data regarding distance, speed, incline, and calories burned while using the treadmill.

How to Check if Your Treadmill Supports It

To check if your treadmill supports connection to your Apple Watch, look for:

1. “Connects to Apple Watch”
2. Apple Watch or GymKit logo displayed on the screen of the treadmill

How to Pair Apple Watch With the Treadmill

To pair your Apple Watch with your treadmill:

1. Begin a workout session on the treadmill.
2. Place the Apple Watch close to the treadmill’s GymKit reader.
3. Approve the connection alert from your watch.
4. Once connected, your workout data syncs automatically throughout the session.

Can You Edit Apple Watch Treadmill Distance After a Run?

While manually deleting workout data or adding health data through the Health app on your iPhone is possible, directly modifying the distance of a completed Apple Watch treadmill workout is still pretty limited. In contrast to other smartwatches for running, such as Garmin or Coros, you won’t find any special treadmill correction function.

So when you notice that the numbers between your treadmill and Apple Watch readings don’t match, you should consider working on better calibration.

Best Apple Watch Settings Before a Treadmill Run

A few simple tweaks before you begin your workout on the indoor treadmill will increase its accuracy.

•  Check your Health Details such as your weight and height, in the Health app on your phone and update, if required.
• Ensure that the “Motion Calibration & Distance” setting on your iPhone is enabled.
• Use the “Indoor Run” feature for runs and “Indoor Walk” for walks on your Apple Watch.
• Try not to hold onto the treadmill railings for too long.
• Swing your watch arm as you would normally while exercising.
• Consider using GymKit or “Connects to Apple Watch” treadmills, if available.
• Don’t use the Apple Watch Low Power Mode during workouts since this affects tracking accuracy.

Wrap Up

Following these steps will definitely help you increase the accuracy of the treadmill workouts on your Apple Watch and get your indoor running closer to the treadmill data despite the occasional mismatch.

In general, Apple Watch should work well enough for monitoring your workouts on a treadmill, your heart rate, the amount of calories burned and other fitness parameters. Even then, if you need an accurate treadmill measurement or pace, the treadmill or GymKit-connected equipment might be more accurate.

Right now, there is one thing that you can do and this is to properly calibrate your Apple Watch, do some outdoor walking or running and then run or walk indoors using Indoor Run or Indoor Walk modes on your Workout app on the Apple Watch.

Frequently Asked Questions