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Altimeter issue

Leew72
over 6 years ago
Anyone else getting false elevation reading on the 645M ?? Mine is consistently overestimating by 600ft.. any way of calibrating this???
  • 0 over 6 years ago
    Yes, mine is about 240ft off. I haven't found a way to calibrate the sensor.
  • 0 over 6 years ago
    This was mentioned in another thread here and was brought up in the comments on DCR in depth review. Ray hadn't noticed it but when it was brought up he said he would contact Garmin and ask what was up.

    I did a search on the 645 manual for "altimeter" and got no results and for "calibration" and only got instructions for calibrating a foot pod. I'm interested to see what the response is.
  • 0 over 6 years ago
    Yep, comparing my 645 with Ordnance Survey UK Maps, it's plus 560ft with no way to calibrate. OK I guess for elevation gain during a run, but not great when hill/mountain climbing in unknown teritory...
  • 0 over 6 years ago
    It sounds strange that you have no way of calibrating the altimeter. As far as I can see, the 645 has a barometric altimeter, and this type of altimeter needs frequent calibration.

    On the more expensive Garmin watches, the calibration can happen in two ways:

    1. When you go into the altimeter widget, there is a manual calibration option.

    2. If auto calibration is enabled, when you start an activity - and wait to press Start until you have a GPS fix! - the watch will calibrate the barometric altimeter from GPS altitude or a stored altitude.

    I don't know the 645, but these two options might be worth looking for.
  • 0 over 6 years ago
    You don’t need to have an expensive Garmin watch to have a manual calibration option for the altimeter or auto calibration. My 2 year old vivoactive HR has both. However, the auto calibration is not always working and I regularly have to manually calibrate the sensor.

    I hope Garmin will add these to the FR645 as well, because I plan to buy it, but without an option to manually calibrate the sensor, I probably won’t.
  • Former Member
    0 Former Member over 6 years ago
    I find it quite strange that there's no way to calibrate the barometric altimeter on this watch. Is it possibly "hidden" somewhere? Maybe it was forgotten in the settings when released and it will be added later? I really can't see it being omitted intentionally. Without calibration on these watches the altimeter readings will become nonsense over a short time. Garmin has to know that. That would make it a deal breaker for a lot of perspective buyers.
  • 0 over 6 years ago
    You don’t need to have an expensive Garmin watch to have a manual calibration option for the altimeter or auto calibration.

    You need to have a watch with a barometric altimeter. This type of altimeter is not in the cheap watches. They only have GPS altitude measurement which does not need calibration.

    These are the facts. I don't want to go into an argument about when a watch can be considered expensive.
  • 0 over 6 years ago
    Even low end Fitbit and Garmin activity tracking bands have barometric altimeters. That's how they count stairs.
  • 0 over 6 years ago
    Even low end Fitbit and Garmin activity tracking bands have barometric altimeters. That's how they count stairs.


    If these watches have a barometric altimeter, but no calibration option, then I suppose that these watches do not show the user an absolute altitude from the barometric altimeter.
  • 0 over 6 years ago
    The low end devices don't tend to show elevation they just use the altimeter to count stairs. The lack of calibration on the 645 has to an oversight since they have it on the VA3?