This is very useful.
y = 4-08x2 - 0.0036x + 99.996
X = your altitude in meters.
Y = the local boiling point (at standard air pressure)
If you know your altitude, it will give you the ‘standard’ boiling temperature.
If you know the local boiling point, you can work backwards to get the altitude where you are standing.
Excel cell contents:
where ‘Altitude’ is the cell in which the altitude is located.