How do I find my height above sea level?

[TSN79]

I'm under the impression that this takes special equipment? We're talking centimeter precision by the way. Shouldn't I be able to get this from some App by now?!

 

[davenn]

It is specialist equip! :)
Top of the line GSP systems I work with will give you 1 to 1.5 cm (10 - 15mm)accuracy at a cost of $20,000 or so because multiple units are needed for that sort of accuracy

standard handheld GSP units like the Garmin E-Trex etc will give down to maybe 3-5 metres of accuracy

Dave

Ohh I should actually qualify that ... We find that the vertical accuracy averages ~ half the quality of horizontal accuracy. So for a horizontal accuracy of 1cm, which under good conditions is quite achievable,
the vertical accuracy will be ~ 2cm