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DRAG RACING CALCULATORDensity Altitude
Density Altitude
Calculator
Estimate moist-air density and corresponding standard-atmosphere altitude from measured station pressure, temperature and relative humidity.
Your setup
°F
Range: -40.00–140 °FinHg
Use measured absolute station pressure, not sea-level-corrected weather pressure or altimeter setting.%
Range: 0.00–100 %Your results
CalculatedEstimated density altitude1,361.63ft
Moist-air density1.18kg/m³
Relative density96.08% ISA sea level
Density altitude is the altitude in a reference atmosphere with equal air density; it is not your measured elevation.
READ THE ASSUMPTIONS
Ideal-gas moist-air model within the stated input bounds and tropospheric approximation. Not for aviation navigation or engine-control calibration.
THE FORMULA
How the calculation works
Follow the formula and keep the input units consistent at every step.
e = RH/100 × 6.1078 × 10^(7.5T/(237.3+T)); ρ = (P−e)100/(287.05Tk) + e100/(461.495Tk); h = 44330.77[1−(ρ/1.225)^(1/4.25588)]- Measure temperature in °C, absolute station pressure in hPa and relative humidity.
- Calculate water-vapor partial pressure and ideal moist-air density in kg/m³.
- Invert standard tropospheric density to estimate equivalent altitude in meters.
A Worked Example
Dry air at 15°C and 1013.25 hPa has density approximately 1.225 kg/m³ and density altitude approximately 0 m. Humidity lowers density at the same temperature and pressure.
What Your Result Means
Density altitude is the altitude in a reference atmosphere with equal air density; it is not your measured elevation.
Assumptions & Limitations
Ideal-gas moist-air model within the stated input bounds and tropospheric approximation. Not for aviation navigation or engine-control calibration.
Common Mistakes
Sea-level-corrected pressure can seriously understate density altitude at an elevated track.
Questions about this calculation
Which values should I enter?
Measure temperature in °C, absolute station pressure in hPa and relative humidity. Sea-level-corrected pressure can seriously understate density altitude at an elevated track.
How should I interpret the result’s precision?
Displayed results are rounded for readability. Intermediate calculations retain floating-point precision; extra displayed decimals do not improve your input accuracy.
Can I use metric units?
Yes. Select Metric above the calculator to convert your inputs. Results always state their units. Tire-size designations keep their conventional mm and inch units.
What are the main limitations?
Ideal-gas moist-air model within the stated input bounds and tropospheric approximation. Not for aviation navigation or engine-control calibration.
Method, sources & relevant guides
Vapor pressure and virtual-temperature method. We calculate ideal moist-air density and invert standard tropospheric density; small rounding differences from the NWS implementation are expected.
NOAA / National Weather Service — Density altitude equationsMethod documentation updated October 18, 2026. Independent professional review has not been claimed. Read the calculation and review policy.