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Barometric Pressure to Altitude Calculator

Estimate altitude above sea level from a barometric pressure reading.

Result

Estimated Altitude
540 m
In Feet
1,773 ft

Uses the international barometric formula, which assumes standard atmospheric conditions - real-world altitude readings from pressure can shift somewhat with actual local weather and temperature, which is why aircraft altimeters are regularly recalibrated to a current local sea-level pressure setting.

About the Pressure to Altitude

The Barometric Pressure to Altitude Calculator estimates how high above sea level you are based on a measured air pressure reading, using the same principle that aircraft altimeters and weather instruments rely on. It's useful for hikers, pilots, weather enthusiasts, or anyone with a barometer trying to translate a pressure reading into an approximate elevation.

How It Works

You enter your measured pressure and a sea-level reference pressure (defaulting to the standard 1013.25 hPa), and the calculator applies the international barometric formula to estimate altitude in meters, then converts that figure to feet as well.

altitude (m) = 44,330 x (1 - (pressure / seaLevelPressure)^(1/5.255)); altitude (ft) = altitude (m) x 3.28084.

Formula & Methodology

The formula models how atmospheric pressure decreases in a predictable, exponential (not linear) way as altitude increases, because air is compressible and gets less dense the higher you go. Plugging in the ratio of your measured pressure to the sea-level reference pressure, raising it to the power of 1/5.255, and subtracting that from 1 before multiplying by the constant 44,330 gives the estimated height in meters at which that pressure would be measured under standard atmospheric conditions.

Examples

A reading below the default sea-level pressure

With a measured pressure of 950 hPa against the standard 1013.25 hPa reference, the ratio is about 0.9376, raised to the 1/5.255 power gives roughly 0.9880, so altitude = 44,330 x (1 - 0.9880) ≈ 532 meters (about 1,745 feet).

A high-altitude reading

With a measured pressure of 700 hPa against the same 1013.25 hPa reference, the ratio is about 0.6909, and the formula works out to an estimated altitude of roughly 3,010 meters (about 9,875 feet), reflecting the steeper pressure drop found at greater heights.

Advantages

  • Uses the same internationally recognized barometric formula found in aviation and meteorology.
  • Lets you adjust the sea-level reference pressure to reflect current local conditions rather than assuming a fixed constant.
  • Returns results in both meters and feet in a single calculation.

Common Mistakes

  • Using a generic 1013.25 hPa sea-level reference when the actual local sea-level pressure that day differs due to weather, which can meaningfully shift the estimated altitude.
  • Treating the result as a perfectly exact elevation rather than an estimate based on standard atmospheric assumptions.
  • Confusing station pressure (measured at your location) with sea-level-adjusted pressure, which are two different figures that a properly calibrated instrument distinguishes.
  • Assuming pressure drops at a constant linear rate with altitude, when the relationship is actually exponential.

Edge Cases to Watch For

  • If either the measured pressure or the sea-level reference pressure is zero or negative, the calculator returns an error instead of an invalid result.
  • The formula assumes standard atmospheric conditions, so real-world weather systems and temperature swings can shift the actual pressure-to-altitude relationship at a given location.
  • Using an outdated or incorrect local sea-level reference pressure (rather than the current one) will skew the estimated altitude, which is why instruments like aircraft altimeters are periodically recalibrated to a fresh local setting.
  • A measured pressure equal to the sea-level reference pressure returns an altitude of 0 meters, since the ratio becomes 1 and the exponential term reduces to 1 minus 1.

Common Use Cases

  • Hikers or backpackers using a barometric altimeter watch or device to cross-check elevation.
  • Pilots and aviation students learning how altimeters translate pressure readings into altitude.
  • Weather hobbyists interpreting barometer readings in terms of estimated elevation.
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why does air pressure decrease with altitude?

Atmospheric pressure at any point is caused by the weight of all the air above it pressing down, so climbing higher means less air remains above you, and therefore less weight and lower pressure - this relationship isn't perfectly linear because air itself is compressible and gets less dense at higher altitudes, which is why the formula uses an exponential rather than a straight-line relationship.

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Conclusion

By applying the standard barometric formula, this calculator converts a pressure reading into a usable altitude estimate in both meters and feet. It offers a solid approximation for general use, with the understanding that real atmospheric conditions can introduce some variation from the standard assumptions.