How accurate are GPS watches?

Nyal

Chapter Presidents
May 13, 2010
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I recently bought a GPS pendant and it is not too accurate. How accurate are the GPS watches?
 
My Forerunner 305 claimed

My Forerunner 305 claimed that I only did 1/3 of a mile this morning but I know it was at least 50 :innocent: ! Oh, OK, I admit it was closer than my estimate :shock:

Putting serious hat on... :grade:

I gather that the signal only ever allows them to position within 10 meters unless you have a military version. The error within that 10 meters changes (so going the same route on different days and then plotting it may show you on the other side of the road for example). This assumes that your gadget can get a "fix" on enough satellites each time, if you are in trees (for example) this will probably cut down the precision further. Even weather / cloud cover may have an effect but for most purposes your typical running GPS watch should be OK to within 10 meters outside on a fine day without too many tall building near it.