Physics

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Air Density Calculator.

Calculate air density using the ideal-gas equation with an explicit gas constant.

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Set your values

Results update as you type.

density: 1.225012

density

1.225012

Use Cases

Engineering and HVAC calculations

Determine air density for ventilation system design, air flow measurements, or thermal comfort analysis.

Example: Calculate air density at 101325 Pa and 293.15 K with R=287.05 J/(kg·K).

Aerodynamic and performance analysis

Estimate air density for vehicle drag, aircraft performance, or wind turbine power output.

Example: Find air density at high altitude with lower pressure and temperature.

Frequently Asked Questions

What is the ideal-gas equation used in this calculator?
The calculator uses the ideal-gas equation: density = pressure / (specific gas constant × temperature). It requires absolute pressure in pascals, absolute temperature in kelvin, and the specific gas constant in J/(kg·K).
Why must pressure and temperature be absolute?
Absolute pressure (Pa) and absolute temperature (K) are required because the ideal-gas law is based on absolute scales. Gauge pressure or Celsius temperatures would give incorrect density values.
What is the typical value for the specific gas constant of air?
For dry air, the specific gas constant is approximately 287.05 J/(kg·K). You can enter this value or adjust it for other gases or humid air conditions.

Tips & Common Mistakes

Tips

  • Use absolute pressure in pascals (Pa), not gauge pressure. Add atmospheric pressure to gauge readings if needed.
  • Convert temperature to kelvin by adding 273.15 to Celsius values.
  • For dry air, use 287.05 J/(kg·K). For humid air, adjust the gas constant or use a specific value.
  • Double-check units: pressure in Pa, temperature in K, and gas constant in J/(kg·K) to get density in kg/m³.

Common Mistakes to Avoid

  • Using gauge pressure instead of absolute pressure, leading to lower density values.
  • Entering temperature in Celsius or Fahrenheit without converting to kelvin.
  • Using the universal gas constant (8.314 J/(mol·K)) instead of the specific gas constant for air.

Last updated: August 13, 2026