Altitude Pressure Calculator
Air pressure from elevation in both units.
What it does
Air thins with height in a fixed curve. At 1,500 meters pressure sits near 845.6 hPa, or 83.5% of sea level, while 5,000 feet gives 843.1 hPa. Engines, wings, weather, and lungs all feel the same drop.
The tool above runs the barometric line. Metric and imperial mirrors describe the same physical hill in different units, landing within a few hectopascals after rounding. Percent of sea level keeps engines and recipes comparable across elevations.
Standard atmosphere fixes the curve for planning. Daily weather wobbles around it, temperature profiles bend it, and humidity nudges density further. Altimeters handle the gap with local pressure settings rather than raw elevation.
This page models the troposphere standard to 12 km. It does not forecast weather, set altimeters, or rate human performance. For flight and health, apply live data on top.
How to use
- Pick metric (m) or imperial (ft).
- Enter the elevation.
- Read pressure in hPa first.
- Read inHg for aviation and weather.
- Read percent of sea level.
- Apply local altimeter settings for flight.
Formula
- h
- Elevation in meters (converted from feet when imperial).
- P0
- Sea level standard, 1013.25 hPa.
- 0.02953
- 29.53 thousandths of inHg per hPa.
US Standard Atmosphere troposphere to 11 km. At zero altitude pressure is sea level. Weather, temperature profile, and humidity shift real readings around standard.
Worked example
Example: 1,500 m elevation
Defaults: metric 1,500 m. Imperial mirror is 5,000 ft. Sea level is 1013.25 hPa.
- Inputs (metric default): 1,500 m elevation.
- Factor: 1 minus 2.2558e-5 times 1500 is 0.966163.
- Power: to the 5.2559 is 0.8345.
- Pressure: 1013.25 times 0.8345 is 845.6 hPa.
- Share: 83.5 % of sea level (24.97 inHg). Imperial 5,000 ft gives 843.1 hPa. Tool shows the same.
Reference table
| Elevation | Pressure | Share |
|---|---|---|
| 1500 m | 845.6 hPa | 83.5 % of sea level |
| 5000 ft | 843.1 hPa | 83.2 % of sea level |
| 0 m | 1013.3 hPa | 100 % of sea level |
| 3000 m | 701.1 hPa | 69.2 % of sea level |
| 10000 ft | 696.8 hPa | 68.8 % of sea level |
Limits
- Standard atmosphere. Weather excluded.
- Troposphere model. Stratosphere differs.
- Dry curve. Humidity nudges density.
- No altimeter setting math.
Common mistakes
- Using feet as meters, off by 3.28x.
- Reading hPa as inHg directly.
- Ignoring temperature inversions.
- Applying sea level power at altitude.
- Flying on elevation without settings.
Try it yourself
Quick checks. Answers sit tucked under each question.
Sea level at 0 m?
Metric 0 m gives 1013.3 hPa (1013.25 rounds to 1013.3), 29.92 inHg, 100 % of sea level.
What about 3,000 m?
At 3000 m the factor gives near 701.1 hPa. Enter 3000 to read it with inHg and percent.
Questions
What is the barometric formula?
P = 1013.25 times (1 minus 2.2558e-5 h)^5.2559, h in meters. Here 845.6 hPa.
How is inHg figured?
hPa times 0.02953. Here 24.97 inHg.
What is percent of sea level?
P / 1013.25 times 100. Here 83.5 % of sea level.
Does this work at Everest heights?
Yes up to about 11 km. Above needs layered atmosphere math.
Is standard exact daily?
No. Weather swings a little around standard. Altimeters correct with local settings.
Why does altitude matter?
Falling pressure with height thins air for engines, wings, and lungs alike.