Pressure to Altitude Calculator

Altitude Formula:

\[ h = \frac{R \times T}{g} \times \ln\left(\frac{P_0}{P}\right) \]

Temperature (T):

Pressure (P):

Gas Constant (R):

J/kg·K

Gravity (g):

m/s²

Reference Pressure (P₀):

Altitude (h): meters

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a Pressure to Altitude Calculator?

Definition: This calculator estimates altitude based on atmospheric pressure using the barometric formula.

Purpose: It's used in aviation, meteorology, and engineering to determine elevation from pressure measurements.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ h = \frac{R \times T}{g} \times \ln\left(\frac{P_0}{P}\right) \]

Where:

\( h \) — Altitude (meters)
\( R \) — Specific gas constant for dry air (287 J/kg·K)
\( T \) — Temperature (Kelvin)
\( g \) — Gravitational acceleration (9.81 m/s²)
\( P_0 \) — Reference pressure at sea level (101325 Pa)
\( P \) — Measured pressure at altitude (Pa)

Explanation: The formula models how atmospheric pressure decreases exponentially with altitude in an isothermal atmosphere.

3. Importance of Pressure-Altitude Calculation

Details: Accurate altitude determination is crucial for aircraft navigation, weather forecasting, and scientific research.

4. Using the Calculator

Tips: Enter the measured pressure, temperature (in Kelvin), and optionally adjust the constants if needed. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the standard sea level pressure?
A: The International Standard Atmosphere defines 101325 Pa (1013.25 hPa) as standard sea level pressure.

Q2: How does temperature affect the calculation?
A: Higher temperatures result in less dense air, making the atmosphere "taller" at a given pressure.

Q3: When would I change the gas constant?
A: The default 287 J/kg·K is for dry air. Use 461.5 J/kg·K for water vapor or adjust for specific humidity.

Q4: How accurate is this calculation?
A: It assumes an isothermal atmosphere. For greater accuracy, use the full atmospheric model with layers.

Q5: Can I use hPa instead of Pa?
A: Yes, but ensure both P₀ and P use the same units (1 hPa = 100 Pa).