Series 9 swim distance inaccurate after watchOS 26

Question

Series 9 swim distance inaccurate after watchOS 26

Hi all,

Looking for advice on a GPS tracking issue that started after updating to watchOS 26.

The problem:

I swim a fixed out-and-back route that's consistently ~2.95 km, confirmed by map overlay and matched by other swimmers' watches — mostly Garmin and other dedicated swim-tracking devices, known for being very precise — on the same swim. Until this year, my Series 9 tracked it accurately too. Now it's recording 3.20+ km on the same route — everyone else is in sync, mine isn't.

What I've tried:

Full calibration reset (Watch app → Privacy → Reset Calibration Data) + a long outdoor walk to rebuild the profile
This fixed it for two swims afterward (accurate results, matched other swimmers)
Third swim, same route/conditions: overestimated again (3.24 km)

Questions:

Anyone else seeing this regression on watchOS 26 for open water swimming specifically?
Anything else worth trying beyond calibration reset (e.g. full unpair/re-pair)?
Any known workarounds?

Thanks!

Apple Watch Series 9, watchOS 26

Posted on Aug 3, 2026 12:45 PM

Reply

Answer 1

Aug 3, 2026 11:49 PM in response to giacomofromiseo

Did you compare the number of swimming strokes that were counted?

Does the workout detect the correct style?

Are you using the default swimming workout or a 3rd party app?

Can you see if your watch lost the GPS signal during the workout?

My Ultra 2 tends to record less distance from time to time, because of the temporary loss of the GPS signal and the therefor estimated route between those points having a good GPS fix.

Reply

Answer 2

Aug 6, 2026 2:55 AM in response to giacomofromiseo

On my Ultra two, the GPS signal is kind all over the place during the Open Water Swim.

The map looks like this:

I have tried to keep the watch was above water almost every stroke I took with my left watch arm.

An Outdoor Cycle or Outdoor Walking workout shows a clear route, almost perfectly alined in Maps with the actual road I took.

Maybe you should also tell Apple Techs directly about your findings by using the Feedback link.

Feedback - Apple Watch - Apple

Reply

Answer 3

Aug 5, 2026 2:01 PM in response to Ingo2711

Yes, the stroke count is accurate.

Yes, it correctly detects freestyle right away.

I'm using the native Workouts app set to Open Water Swim.

Neither during the swim nor on the final route map do I see anything indicating a lost GPS signal.

Today I had yet another error: while everyone else's smartwatches recorded between 4.49 and 4.46 km, mine showed 4.63 km. It's super inaccurate, which also makes the recorded pace per 100m completely useless. If they release a feature like this, they must have tested it—didn't they notice these errors?!

Reply