Atmospheric Pressure at Altitude Calculator
Find the standard atmospheric pressure at your site elevation and convert between gauge and absolute pressure, or estimate altitude from a barometric reading.
- P = 101,325 × (1 − 2.25577 × 10⁻⁵ × h)5.25588 = 94,776 Pa
- Absolute = gauge + atmospheric
Standard Atmosphere Formula
Pabs = Pgauge + Patm
h is altitude in metres (valid up to 11 km). Actual barometric pressure varies with weather by about ±30 mbar around this standard value.
Worked example
Pune lies at about 560 m, where standard atmospheric pressure is 947.8 mbar. A reading of 5 bar gauge is therefore about 5.95 bar absolute, not 6.01.
Frequently Asked Questions
How much does atmospheric pressure fall with altitude?
About 12 mbar per 100 m near sea level, falling to about half at 5,500 m.
How do I convert barg to bara?
Add the local atmospheric pressure: bar(a) = bar(g) + about 1.013 at sea level, less at altitude.
Why does altitude matter for instruments?
It affects absolute and gauge conversions, gas density, compressor capacity and the boiling point of water.
Learn more on the blog
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