GPS accuracy? (Read 1515 times)

    So, when I run a 5K on a course that advertises to be certified, and my watches reads exactly 3.1 miles, should I be suspicious? This has happened a couple times already. Just one of those things that makes me go hmmm...


    I run the same 5k race many times in the year. Sometimes my gps reads exactly 5.0 km, on other occasions it can be as much as 250m either way (remember this is the same person, running the same route, using the same gps device). I don't think you can really conclude anything from a single reading - other than the true distance you've run is probably somewhere within the measured distance +- 5%. On average it's more accurate than that, but any one reading can be out by some way.


    Straighter courses tend to be get more accurate readings, and courses away from hills, buildings, trees etc. tend to get better readings, IME.

    De-slacking in progress

      writing with gps watch



      I took great care in pre-spelling and laying out the letters on the beach BEFORE I turned on my Garmin 305. I was at Isle Of Palms S.C. (by Charleston). We walked out the letters dragging out feet so I could retrace the letters with my watch on. As you can see even by doing so the letters "S" in Isle and the the letter "F" in "OF" didn't come out as expected. The S is Isle was the same height as the "I" in Isle and also the cross bar doesn't show in the "A" in the word PAlms. Also the bars in the "F" did show"

      So YES there is always some error in the GPS. Kind of made me made because of the planning we put into the 50 foot tall letters. I was hoping for better results.

      started running @ age 48 [lost 70#+, quit a 30 year pack/day habit>> ran HM]  Ran a few years then quit. Gained 70#+ back and smoking like before. Time to get healthy again @ 52 years over with the C25K program and beyond again. RE-start date 1-13-14