02/2018

Conversion of Absolute Atmospheric Pressure
to Sea Level Pressure

Precision measurements of atmospheric pressure using Wiring/Arduino
with BMP85/180/280 and BME280 sensors

Formulas

1. The BOSCH formula assumes a standard temperature of 15 degrees Celsius. This formula is good when placing a barometer in the interior:

p0 = p / pow(1.0 - h / 44330.0, 5.255);

2. Babinet's formula. The formula is very accurate for altitudes less than 500m:

p0 = - p * (h + 16000.0 + 64.0 * t) / (h - 16000.0 - 64.0 * t);

3. Modified ICAO formula. Probably the most versatile formula:

p0 = p / pow(1.0 - 0.0065 * h / (t + 273.15), 5.255);

Symbol Unit Description
p0 [Pa] Pressure at sea level
p [Pa] Absolute pressure obtained by measurement
t [°C] Air temperature in degrees Celsius
h [m] Altitude of the measuring station