Calculate air density (kg/m³) at a given pressure and temperature using the ideal gas law.

Air density: 1.225 kg/m³

Formula: ρ = P × M / (R × T). Uses dry air molar mass (0.0289644 kg/mol). Humidity is not accounted for.

What Is Air Density and How Is It Calculated?

Air density is the mass of air per unit volume. It is a critical parameter in aviation, meteorology, engineering, and HVAC system design[citation:2]. The density of air is not constant — it depends heavily on pressure and temperature.

Air can be treated as an ideal gas for most practical calculations[citation:4]. According to the ideal gas law:

ρ = P × M / (R × T)

Where:

• ρ — air density (kg/m³)
• P — absolute pressure (Pa)
• M — molar mass of dry air (0.0289644 kg/mol)
• R — universal gas constant (8.314462618 J/(mol·K))
• T — temperature (K)

As pressure increases, air molecules are packed more tightly, so density increases. As temperature rises, air expands and its density decreases[citation:3][citation:4]. At standard sea-level conditions (101.325 kPa, 15°C), air density is about 1.225 kg/m³[citation:2].

Note: This calculator uses dry air molar mass and does not account for humidity. Moist air is slightly less dense than dry air at the same temperature and pressure[citation:6].

How to Use This Calculator

1. Enter absolute pressure: Input the pressure in kilopascals (kPa). Standard atmospheric pressure at sea level is 101.325 kPa.
2. Enter temperature: Input the air temperature in degrees Celsius (°C). Valid range: -100 to 1600°C.
3. Calculate: Click “Calculate Density” or press Enter.
4. Reset: Use the “Reset” button to restore default values.
5. Interpretation: The result shows air density in kg/m³. For example, at 101.325 kPa and 15°C, density is 1.225 kg/m³.