GPS watch inaccuracy....is that a thing?

This happens to any GPS device.

From watches, car navigation and even satellite radio.

This occurs from poor GPS connectivity when it is gathering up enough satellites to make the coordinate pairs or even after.

"Poor" can be a number of reasons... from foliage, excess cloud cover (esp. heavy storms), radio interference (such as microwave ovens, point-to-point data links, WiFi, Bluetooth, etc), or even solar flares from the Sun's Coronal Mass Ejections.

When this happens, I typically stop running (pause/stop the watch if I want to), and wait a minute or two to have it fully reconnect again.

Another tip: When you have your watch start "looking" for the satellites, even after it says it's good to go, I always wait a minute or two before starting my run. Another way to make it gather the satellites even quicker is to take it off your wrist and set it out in the open.

Nothing wrong with your watch, just the nature of GPS.

I have the same problem on the treadmill. Im running just as hard as I ever have but the obviously innacurate treadmill panel tells me I am running at least a minute slower than I obviously am.

If you upload your run to Strava or another site, you can look at the map of what the GPS tracked. If you see any real weird jumps in the data then the watch or signal got messed up. Especially if you had trees or big buildings in the way.

Look at Camille Herrons Garmin after her 24 hour run on a track. Her watch read 10+ miles more than what she actually ran. Proof of Garmins inaccuracy.

Not accurate wrote:

Look at Camille Herrons Garmin after her 24 hour run on a track. Her watch read 10+ miles more than what she actually ran. Proof of Garmins inaccuracy.

Those miles could have been bathroom breaks. They don't put the porta potties right in lane 1.

Sounds like you had no signal at all and it fell back to the accelerometer/cadence to estimate distance. If you look at the map via Strava or Garmin connect or whatever you'll see whether it looks right or not.

Not accurate wrote:

Look at Camille Herrons Garmin after her 24 hour run on a track. Her watch read 10+ miles more than what she actually ran. Proof of Garmins inaccuracy.

Camille Herron doesn't use a Garmin.