Barometric Altitude

This formula estimates the height of a location above sea level from the measured air pressure there, using the fact that atmospheric pressure drops as you go upward because there is less air above you. The exponent and constant come from a standard atmosphere model that approximates how air density decreases with altitude under typical Earth conditions. It is a practical approximation, not an exact law, so it works best for moderate altitudes and ordinary weather conditions.

Use this when you have a pressure reading and want a quick estimate of elevation, such as in surveying, hiking, aviation, or field science. It is also useful for converting barometer readings into altitude differences between two locations when sea-level pressure is known or can be estimated.

• Using local weather-station pressure and calling it sea-level pressure without converting or checking consistency
• Entering pressure in different units for P and P0, which makes the ratio meaningless
• Treating the result as exact even though temperature changes, humidity, and weather systems can shift pressure and affect the estimate