How to Calculate Barometric Pressure from Elevation

Barometric pressure is atmospheric pressure as measured by a barometer. Barometric pressure decreases with altitude because there is less atmosphere above you as you go higher in altitude. Eventually, if you get high enough in the atmosphere, barometric pressure will be so low that it won't be readable at all. With a barometric pressure calculator, it is easy to determine barometric pressure from elevation. You can also use the barometric formula, which is a more complex equation, to arrive at a more accurate pressure at altitude.

Things You'll Need

• Altimeter
• Topography map
• Computer with Internet access
• Barometer

Instructions

1. Determine your elevation. You will need an altimeter to do so. You can also use a topography map, or, if you are at a landmark with a known elevation, you can use that number.

2. Use a simple barometric pressure calculator. They are available online for free, and depending on the one you use, you will need to enter your altitude into it using either meters or feet. Once you enter in the data, the calculator will give you an estimated barometric pressure for that altitude.

3. Use the more complex barometric formula. There is an online version located in reference 2. You enter the pressure and temperature at sea level. You then enter the elevation for which you want the atmospheric pressure calculated. The formula will then calculate the barometric pressure at the elevation you've specified.

Tips & Warnings

• Depending on where you are, you could also use a National Weather Service reporting station, if there is one nearby. Or you could use a barometer to give you an exact barometric pressure reading at altitude.

References

• Altitude.org: Barometric Pressure Calculator
• The Barometric Formula