Air Pressure at Altitude Calculator
Standard pressure at any altitude in hPa, inHg, psi and mmHg — with the percentage of sea level that explains ears, chip bags and turbo controllers alike.
The everyday physics dial: ears pop on the drive to 7,000 ft (77% pressure), chip bags balloon at altitude, water boils at 90 °C in Leadville, and turbo wastegates spend their lives fighting exactly this curve.
Formula
⚠️ For planning and education only. Weight & balance must be computed from YOUR aircraft's actual empty weight, arm and current equipment list, and verified against the POH/AFM envelope before flight.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Standard pressure at any altitude in hPa, inHg, psi and mmHg — with the percentage of sea level that explains ears, chip bags and turbo controllers alike.
About Air Pressure at Altitude Calculator
Air pressure falls predictably with altitude — about 1 hPa per 27 feet near sea level, easing to an exponential fade aloft — and the consequences run from popping ears to engine ratings. This calculator returns the ISA pressure at any altitude in the four units different fields insist on (hPa, inHg, psi, mmHg-adjacent), plus the intuitive percentage of sea level, with both atmospheric regimes modeled correctly.
How to use Air Pressure at Altitude Calculator
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula p = 1013.25 × (1 − 6.5h/288150)^5.2559 hPa (troposphere); exponential above 11 km substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Air Pressure at Altitude Calculator?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula p = 1013.25 × (1 − 6.5h/288150)^5.2559 hPa (troposphere); exponential above 11 km with sources cited on the page
- ✓The everyday physics dial: ears pop on the drive to 7,000 ft (77% pressure), chip bags balloon at altitude, water boils at 90 °C in Leadville, and turbo wastegates spend their lives fighting exactly this curve.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
What is the air pressure at 10,000 feet?+
697 hPa in the standard atmosphere — 68.8% of sea level, 20.58 inHg, 10.1 psi. It's the cabin-altitude ceiling for unpressurized comfort decisions and the regulatory line where Part 135 crews don oxygen. Real-day values wander a couple percent either way with weather; the ISA figure is the planning anchor.
Why does pressure fall faster low down than high up?+
Pressure at any height is the weight of air above, and that air compresses under its own weight: dense low-altitude air stacks more weight per foot of climb. The result is near-exponential decay — half the atmosphere below 18,000 ft, half the remainder by 36,000, never quite reaching zero (orbital altitudes still see drag).
How does this curve govern turbocharger behavior?+
A turbo's job is to rebuild this curve's losses: the wastegate stays partly open at sea level and closes progressively with altitude to hold sea-level manifold pressure, reaching fully-closed at the critical altitude — the height where ambient has fallen as far as the compressor can compensate. The pressure curve on this page IS the wastegate's schedule.
Does temperature change the pressure at a given altitude?+
On a given day, yes — warm columns are 'thicker' (pressure falls more slowly with height), which is exactly the high-to-low altimeter error and the geopotential-height story on weather charts. ISA fixes one reference column so calculations agree; the deviations are the weather, and other tools on this site price them.
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