Indoor run is inaccurate

This answer doesn’t get to the root of the problem - if I run a fixed distance on a treadmill, why can’t I correct the distance my Apple Watch is displaying? I’ve calibrated my watch several times and I’m regularly getting indoor distances on my watch that are 20-25% off, like being told I ran 2.3 miles when I ran 3 on the treadmill. This seems like something that should be super obvious

I agree with the comments on manually editing run data - it should be a standard function like what is provided in the Nike Run Club app (albeit only on the iPhone, which is another frustration but a different topic). I will lodge a feature request, but if my experience of this is anything to go by it wont get addressed (e.g. Apple Pay history on watch payments repeated requests, but still nowhere to be found even though we’ve reached watchOS 4 😕).

I’m not impressed with the accelerometer function in the watch having previously owned a Series 0 and now a Series 3 nike plus edition. IMO the old shoe pod Nike + solution was a much better indoor treadmill distance tracker than the Watch. I used to get only a ~100m delta on a 5km run. No matter what I do to try and calibrate the watch with GPS runs outside its consistently 500-600m down on the low side.

At least I’ve found the GPS tracking is pretty decent outside - at least the equivalent accuracy of my iPhone on runs I know well.

Hi

It may help to reset your calibration data and to recalibrate your Apple Watch, being sure to allow the arm on which you are wearing your Apple Watch to swing naturally both during calibration and during subsequent treadmill-based workouts. Resetting calibration data will not erase historic Activity data.

More information and instructions:

Calibrating your Apple Watch for improved Workout and Activity accuracy - Apple Support

Hi

Manual calibration with data from a treadmill is not currently supported. If you would like to submit a feature request to Apple, then you can do so here:

Feedback - Apple Watch - Apple

Apple has recently announced GymKit, which will enable Apple Watch users to connect their Apple Watch to certain gym cardio equipment, with two-way data synchronisation.

A capability that was added in watchOS 4, GymKit will enable Apple Watch to connect with treadmills, ellipticals, indoor bikes and stair steppers from manufacturers such as Life Fitness, StairMaster and Technogym.

Participating equipment manufacturers and gyms may vary.

Update: having reset and recalibrated using GPS a few times over the weekend I’ve finally got the Series 3 watch a lot closer to the treadmill number when running indoors. Now only 30-50m out over a 5km run.

Much happier now 🙂

Seems that on the treadmill you are taking longer strides than you do outdoors since indoor the watch records step/arm movements.

I notice a similar reduced milage when I run on treadmill compared with outdoor run.

Great - thank for your following up! 🙂