Atmospheric Pressure at Elevation Calculator & Formula

This atmospheric pressure at elevation calculator estimates air pressure above or below sea level using elevation and the standard-atmosphere model. Enter elevation in meters to get estimated pressure in kilopascals and standard atmospheres; actual weather and local conditions can make measured pressure differ.

Formula

For elevations in the lower part of the standard atmosphere, the calculator uses the barometric pressure relation:

p = p₀ × (1 − Lh / T₀)^(gM / (RL))

• p is estimated absolute atmospheric pressure, in kilopascals (kPa).
• p₀ is standard sea-level pressure, 101.325 kPa.
• h is elevation above mean sea level, in meters (m); elevations below sea level are negative.
• L is the standard temperature lapse rate, 0.0065 kelvin per meter.
• T₀ is standard sea-level temperature, 288.15 kelvin.
• g is standard gravitational acceleration, 9.80665 meters per second squared.
• M is the molar mass of dry air, approximately 0.0289644 kilograms per mole.
• R is the universal gas constant, approximately 8.31446 joules per mole per kelvin.

Combining the constants gives the calculator form: p = 101.325 × (1 − 0.0000225577h)^5.25588. Pressure in standard atmospheres is pₐ = p / 101.325. One standard atmosphere is 101.325 kPa, or 14.6959 pounds per square inch (psi). The equation assumes the standard temperature profile and is intended for the troposphere, roughly up to 11,000 m.

Worked Example

With the default elevation of 1,000 m:

1. Calculate the bracket: 1 − (0.0000225577 × 1,000) = 0.9774423.
2. Raise it to the stated exponent: 0.9774423^5.25588 ≈ 0.88699.
3. Multiply by standard sea-level pressure: 101.325 × 0.88699 ≈ 89.87 kPa.
4. Convert to atmospheres: 89.87 / 101.325 ≈ 0.8871 atm.

The outputs are rounded to the decimal places specified in the calculator.

What the Calculator Estimates

Atmospheric pressure is the force per unit area exerted by the air above a location. At higher elevations there is less air overhead, so pressure generally decreases. The calculator estimates absolute pressure: pressure relative to a vacuum, not pressure relative to the surrounding air.

At sea level under standard conditions, pressure is 101.325 kPa, equal to 1 atm or about 14.70 psi. At 1,000 m in the example, the estimate is about 89.87 kPa, or 13.04 psi. These are equivalent ways to express the same pressure, not separate measurements.

When to Use an Elevation Estimate

This calculation is useful for understanding how elevation changes the standard reference pressure, comparing locations at different heights, or getting a rough estimate when no local pressure observation is available. It can also help explain why a weather station’s pressure reading may need adjustment before comparing it with a sea-level-referenced weather report.

Use the elevation above mean sea level, not the height of a building, hill, or instrument above the ground unless that height has been added to the site’s elevation. For example, a sensor 30 m above ground at a site 1,000 m above sea level is approximately at 1,030 m elevation.

Standard Pressure Versus Local Weather

The standard atmosphere is a reference model, not a promise about the pressure outside on a particular day. Real pressure changes with weather systems, temperature, humidity, and other atmospheric conditions. A barometer measures the pressure at its location and may report station pressure, while weather forecasts commonly display pressure adjusted to sea level to make places at different elevations easier to compare.

Consequently, an elevation-only calculator cannot reproduce a live barometer reading or a location-specific forecast. If you need the actual pressure, use a calibrated instrument or a current observation for the precise location and time. Also check whether a reported figure is station pressure or sea-level pressure; confusing them can make readings appear substantially different at high elevation.

Units, Range, and Common Mistakes

The input is in meters. To convert feet to meters, multiply the elevation in feet by 0.3048. For instance, 3,281 ft is approximately 1,000 m. Do not enter a value in feet as though it were meters: that would make the calculated pressure much too low for the intended location.

• The calculator accepts elevations from −500 m through 11,000 m, the range used for this standard-model estimate.
• Negative elevation means below mean sea level; it does not mean negative pressure.
• Do not treat 1 atm as the expected local pressure at every elevation. It is the standard sea-level reference.
• Keep more digits during conversions and round only the displayed result. Small differences from a barometer are expected because the model omits current weather conditions.

Pressure conversions can provide useful context: 1 kPa is 1,000 pascals, and 1 psi is approximately 6.895 kPa. To convert the output to psi, divide kPa by 6.895. A result in atm is a ratio to standard sea-level pressure; it is not an elevation or a measure of relative, gauge pressure.

Frequently Asked Questions

How much does atmospheric pressure change with elevation?
It decreases nonlinearly as elevation rises. Near sea level, a small height increase produces a modest pressure reduction, but the exact change is not a fixed amount per meter. The standard-atmosphere equation accounts for that curvature.

What is the atmospheric pressure at 1,000 meters?
The standard-atmosphere estimate is about 89.87 kPa, or 0.8871 atm. Actual pressure at a particular place and time can be higher or lower due to weather.

Is atmospheric pressure the same as air pressure?
In ordinary usage, yes: atmospheric pressure is the pressure exerted by the surrounding air. It is usually an absolute pressure unless a gauge or instrument description says otherwise.

Why does a weather app show a different pressure?
It may show pressure adjusted to sea level, while the calculator estimates pressure at the stated elevation under standard conditions. Weather itself also changes pressure, so compare readings with the same reference and for the same time and location.

Can this calculator give pressure above 11,000 meters?
No. Its formula uses the standard temperature lapse rate for the lower atmosphere and is limited to 11,000 m. Higher atmospheric layers need different reference equations and temperature assumptions.

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in h | Elevation | m | 1000 | -500 | 11000
out p | Pressure | kPa | 101.325 * (1 - 0.0000225577 * h)^5.25588 | 2
out a | Pressure | atm | p / 101.325 | 4