GPSrChive Discussion Forum

Hi all,

I recently purchased a GPSMAP 67. I am having problems with Altimeter Calibration. On my first hike I set Auto Calibration to Continuous but this setting does not seem to work at all. I have the newest firmware 9.10 on my device.

When I started my hike I began a new recording of the track ... the Barometric Altitude did not calibrate with the GPS altitude shown on the device (although I had perfect satellite coverage). The difference between GPS and Barometric altitude was only 10m. So I did not calibrate manually.

During my hike the difference between GPS and Barometric altitude began to grow ... after about 500 vertical meters the difference was over 50m. At a place where I knew the exact height I calibrated manually but after another 200 vertical meters the device again showed a difference of almost 40m between GPS and Barometric altitude. All the time the GPS altitude was correct, the barometric altitude was incorrect.

At home I set the Auto Calibration to Once and started a new recording. With this setting it also does not calibrate to the GPS altitude which is correct. It always shows and records the wrong Barometric altitude. The only thing that works is the Manuell Calibration ...

Any hints what I may be doing wrong? Why does the calibration settings Continuous and Once not work?

crowdsalad wrote: Sun Sep 14, 2025 8:40 am When I started my hike I began a new recording of the track ... the Barometric Altitude did not calibrate with the GPS altitude shown on the device (although I had perfect satellite coverage). The difference between GPS and Barometric altitude was only 10m. So I did not calibrate manually.

GPS Elevation is almost always the least accurate measurement available.

Barometric calibrated Elevation is almost always going to more accurate than GPS calibrate Elevation.

Please reference the following pages for detailed explanations:

GPSrChive > GPSMAP 67 > Main Menu > Altimeter

GPSrChive > GPSMAP 67 > Setup > Altimeter

GPSrChive > How To... > Altimeter

crowdsalad wrote: Sun Sep 14, 2025 8:40 am At home I set the Auto Calibration to Once and started a new recording. With this setting it also does not calibrate to the GPS altitude which is correct. It always shows and records the wrong Barometric altitude. The only thing that works is the Manuell Calibration ...

Perform two tests to verify that the altimeter is working properly.

First attempt:

Delete the last activity record, set the calibration to "At Power On," disable "Auto Start," and restart the device.

Observe the "Altitude" and "GPS Altitude" data fields; the values ​​displayed in both fields may be different.

Wait a moment until the GPS signal is fully established, and then enable "Activity" recording. The "Altitude" data field should still have a value very close to the "GPS Altitude" value.

Second attempt:

Do everything as before, but before enabling "Activity" recording, perform a manual calibration. Enter a value 30 meters lower or higher (delete the previous "Activity" value).

After enabling "Activity" recording, the "Altitude" data field should display the manual calibration value; the "GPS Altitude" field will display a value close to the current altitude.

Always archive and delete the previous "Activity" recording before turning on the recording, start the Activity recording when the GPS signal is full.