Tech help - smart phone altimeters

[MontyVeda]

After discovering the GPS inaccuracies of my Garmin watch... I wondered if my smart(ish) phone had an inbuilt altimeter, and apparently it does, although it might just be a barometer that estimates altitude from that.

It's not a new phone; Samsung Note 3... so i found a free app called Galaxy Sensors that'll run on it and according to that, my current altitude is around 177 meters. According to the OS map on Bing, the street outside is around 20 meters and I'm on the first floor (2nd of you're American or a naïve Brit)
So I installed another freebie altimeter app that can be calibrated, but apparently is quite accurate out of the box, that puts me at -176meters I plan to go to the nearest trig point and calibrate it... but how on earth can it think I'm that far below sea level?

Any tips on making the inbuilt altimeter any more accurate (can't find anything in settings)... or an app I can trust?

 

[Milkfloat]

What altitude is the gps giving?

 

[MontyVeda]

What altitude is the gps giving?

according to whataltitude[dot]com, 23m, which seems about bang on.

 

[Milkfloat]

according to whataltitude[dot]com, 23m, which seems about bang on.

I meant on the Galaxy Note. GPS altitude can be ropey at best, I was wondering if the barometer on the watch was also using the gps to calculate altitude.

 

[Alex321]

After discovering the GPS inaccuracies of my Garmin watch... I wondered if my smart(ish) phone had an inbuilt altimeter, and apparently it does, although it might just be a barometer that estimates altitude from that.

It's not a new phone; Samsung Note 3... so i found a free app called Galaxy Sensors that'll run on it and according to that, my current altitude is around 177 meters. According to the OS map on Bing, the street outside is around 20 meters and I'm on the first floor (2nd of you're American or a naïve Brit)
So I installed another freebie altimeter app that can be calibrated, but apparently is quite accurate out of the box, that puts me at -176meters I plan to go to the nearest trig point and calibrate it... but how on earth can it think I'm that far below sea level?

Any tips on making the inbuilt altimeter any more accurate (can't find anything in settings)... or an app I can trust?

A barometer for absolute altitude is always going to be very iffy, because air pressure varies considerably with the weather.

It is OK for showing changes in altitude, provided the weather doesn't change at the same time. Some devices will cross check against GPS data, but I'm still not convinced they are very good for absolute altitude.

If you have a way of setting the real current altitude at the start of your activity, and the weather is reasonably constant during it, then a reasonable one should be fairly accurate.

 

[cougie uk]

according to whataltitude[dot]com, 23m, which seems about bang on.

According to that - from the web I'm 138 feet and that ties in perfectly with my Strava app.

I'd just use Strava tbh.

 

[MontyVeda]

I meant on the Galaxy Note. GPS altitude can be ropey at best, I was wondering if the barometer on the watch was also using the gps to calculate altitude.

I checked whataltitude on the Galaxy Note, and you did ask for the GPS altitude


The barometric altitude on the Note is as stated in the OP... one app says I'm 178m above sea level, and other says I'm 175m below sea level.

i think the Garmin watch solely uses GPS to calculate altitude

 

[Alex321]

Just for context, looking at yesterday's ride on my Wahoo, it gives a minimum of 24m, max of 131, with 382m of climbing and 376 descending (in 15.5 miles). Looking at the OS map (via Bing), the lowest contour I can see that I crossed is at 30m, and the highest is at 130, so it is closer than I thought it might be. The start/end point is at 65m.

 

[MontyVeda]

According to that - from the web I'm 138 feet and that ties in perfectly with my Strava app.

I'd just use Strava tbh.

But Strava, like my GPS watch, won't accurately pinpoint my actual location. See my other thread about riding along the canal to find out just how inaccurate GPS can be on its own.

 

[Alex321]

Just installed an app on my phone (Samsung S10), which gives a variety of values.

According to, barometric altitude puts me at 171 feet, location based altimeter puts me at 35 feet, and GPS puts me at 298 feet. According to OS, I'm on the 65m contour, which is 213 feet.

Apparently the barometric altitude is comparing the reading to the latest value from St Athan, 6.2 miles away, and adjusting that to sea level.

 

[MontyVeda]

Just installed an app on my phone (Samsung S10), which gives a variety of values.

According to, barometric altitude puts me at 171 feet, location based altimeter puts me at 35 feet, and GPS puts me at 298 feet. According to OS, I'm on the 65m contour, which is 213 feet.

Apparently the barometric altitude is comparing the reading to the latest value from St Athan, 6.2 miles away, and adjusting that to sea level.

Like an altitude bag of Revels

Which app is it?

 

[DaveReading]

A barometer for absolute altitude is always going to be very iffy, because air pressure varies considerably with the weather.

Indeed so.

Aircraft pilots have a subscale on their altimeter that allows the datum to be adjusted.

If it helps, the height reading on any barometric altimeter should vary by about 28 feet for every millibar (or hectopascal) difference in atmospheric pressure.

 

[Alex321]

Like an altitude bag of Revels

Which app is it?

This one.
https://play.google.com/store/apps/details?id=com.arlabsmobile.altimeterfree&gl=GB

BTW, I mistyped above - the 35 feet should have been 235 feet for the location based one.

 

[cougie uk]

But Strava, like my GPS watch, won't accurately pinpoint my actual location. See my other thread about riding along the canal to find out just how inaccurate GPS can be on its own.

I've used Strava since it began over here. It's always pinpointed me accurately enough. So I can see which side of the road I'm on etc.
Why would you need to be more accurate than that ?

I've used it from my phones and now my Garmin watch and bike computer. Accurate enough to tie in with official distance over running races etc. Apart from the London marathon where the skyscrapers and underpasses bounce the signal around too much.

 

[Ming the Merciless]

You are not going to get a good gps reading inside your flat. It’ll have a limited view of the satellites and may be seeing bounced signals. What’s the reading like when you are outside in open space?