Garmin 305 Under-measuring distances?

LS21LS21 ✭✭✭

Hello all,

Sorry for yet another Garmin thread but I've had a quick look if I can find anything re this problem on here and I can't. Basically I think my Garmin is slightly under-measuring the distances I run.

In my last 4 training runs I've downloaded the info into Sport Tracks and on each occasion the distance Sport Tracks says I've covered is about 0.25 of a mile further than my Garmin says. Then on Saturday I ran a 10 mile race (exactly 10 miles on SportTracks too) but again my Garmin says 9.80 miles.

Anyone had anything similar and if so is there an easy remedy? It's not a massive problem really, but one I'd like to sort out even if it's just to view my mile splits accurately.

Any help gratefully received!


  • ST always says slightly more that my Garmin. I think  it has a slightly different algorithm for working out the distance/error from the raw data contained in the garmin. I have wondered which was better but found no satisfactory answers although from waht you say ST sounds more accurate (Assumign the course was). I am sticking with the pessimisitc Garmin calcs because it means things are simple. I am only looking at one set of figures and means I wont get any nasty surprises when I realise how slow I am in a race!
  • LS21LS21 ✭✭✭

    OK cheers for that - makes sense!! It's not a problem as such really - more just a little bit annoying I guess, but only cos I usually pour over my stats and mile splits afterwards and try to work out where I've lost time.

    It's only really started doing it in the last 2 weeks or so too (seemingly) - there was often a 0.05 or so difference between Garmin and SportTracks but that's by the by really - but when I've been getting differences of 0.3 of a mile I had wondered if something was maybe wrong.

    Not to worry - I think I'll just crack on and adopt your strategy - sounds good advice!

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