Outdoor Run distance increased after updating to watchOS 27

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Level 1

18 points

Outdoor Run distance increased after updating to watchOS 27

I have a known 5.00-mile route that I've run and measured for years. Immediatlely after updating to watchOS 27, my first run with the new software was recorded as 5.20 miles (+4%). Same route was accurate before watchOS 27 in a range from 4.95 to 5.05 miles. Something has changed ... and is demonstrably wrong, at least for my route. I have Strava logs of me running this same route for years if anyone wants to look into this.

Apple Watch Ultra 2, watchOS 27

Posted on Sep 16, 2026 6:43 AM

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Answer 1

Sep 18, 2026 8:22 AM in response to rvnash

There is a calibration feature that can be reset and then performed again. These recalibration doesn’t just happen over one or two workouts. Today, after 4 previous workouts, it’s now within about 100 feet of a he distance.

Personally, I’d give it 3 or 4, workouts. Then contact Apple Support. The other options are to do the calibration and/or unpair your Apple Watch and iPhone and the re-pair them.

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Answer 2

Sep 16, 2026 7:20 AM in response to rvnash

Hi, this is not Apple Support. Apple Support does not participate here, this is a user to user discussion forum. In my experience having upgraded my Ultra for the last 4 years, it may take a few days for the watch to relearn some some measurements. I noticed my route was a little shorter on Monday, but is gradually adjusting to the accurate distance. I'd give it a few days before discussing with Apple support. Have you done a forced restart since upgrading?

If your Apple Watch is stuck on the Apple logo - Apple Support

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Answer 3

Sep 16, 2026 7:45 AM in response to rvnash

As far as I remember, Apple changed something in counting steps in workouts in iOS / watchOS 27.

Did you try to calibrate your watch again, if the issue persists?

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

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Answer 4

rvnash Author

Level 1

18 points

Sep 18, 2026 8:01 AM in response to rvnash

UPDATE:

After taking all of the suggestions above, I ran my normal M/W/F route again this morning ... and it got slightly worse, 5.23 miles. I know for a fact this run is nearly exactly 5.00 miles, as I've been running it for literally decades and measured it across many different devices. Always within a few hundredths of 5.00 miles. Now, with this software update, it's way off. I'm convinced they introduced a bug.

I've submitted it to Apple as a bug. I hope they fix it.

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Answer 5

rvnash Author

Level 1

18 points

Oct 6, 2026 11:29 AM in response to rvnash

Just an update in case anyone is still following. Here are the latest numbers from the GPS distance of my know 5 mile run.

5.03

5.01

5.07

5.20 <- Installed WatchOS 27

5.23

5.07 <- Seemed to recalibrate on its own

5.09

5.07

5.06

5.12 <- Creeping back up again ....?

Anyway, it is getting better on its own. Maybe the last run was a bit of an anomaly.

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Answer 6

Sep 16, 2026 8:17 AM in response to rvnash

rvnash wrote:

No, I have not done a forced restart. I'll do that and do a few more runs and hopefully it will settle back in. Thanks for sharing your experience.

You’re welcome and I hope you have a great day.

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Answer 7

Sep 17, 2026 7:36 AM in response to rvnash

I have same issue with new OS. 27.

WATCH measured my walking route accurately before new OS. Now it is off by over 25%.

it used to work accurately.

Steve Jobs would have never permitted what they changed in the new software.

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Answer 8

Sep 17, 2026 8:20 AM in response to Rocketman3210

Rocketman3210 wrote:

I have same issue with new OS. 27.

WATCH measured my walking route accurately before new OS. Now it is off by over 25%.

it used to work accurately.

Steve Jobs would have never permitted what they changed in the new software.

I worked for Mr. Jobs and hold him in the highest esteem. But it's naive to think that defective software was not produced under his reign. I remember when an update was released, on a Friday, that introduced a new memory check before starting up the computer. Almost every machine failed to start because the tolerances were too tight. Nothing was done until Monday morning and a patch was released. I'm sure you're not suggesting that you'd rather have your watch just quit and not startup.

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