Air Density Correction Calculator
Air density from temperature and altitude for fan corrections.
Enter your values
Enter the air temperature in F.
Enter the altitude in ft.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Air density
- 3.9954 lb/ft3
- Density ratio vs standard
- 53.272
- Barometric pressure
- 29.92 in Hg
- Fan pressure/power correction factor
- 53.272
Quick answer
Air density falls with rising temperature and rising altitude, and fan pressure and power scale directly with density.
rho = P / (R x T); density ratio vs 0.075 lb/ft3 standard
At a glance
| What it does | Air density from temperature and altitude for fan corrections. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Air temperature, Altitude |
| Main output | Air density |
| Formula | rho = P / (R x T); density ratio vs 0.075 lb/ft3 standard |
| Cost | Free — no sign-up, no download |
How to use the Air Density Correction Calculator
- 1Enter the actual air temperature and site altitude.
- 2Read the resulting air density and its ratio to standard air (0.075 lb/ft3 at sea level, 70F).
- 3Multiply catalogue fan pressure and horsepower ratings by this ratio for accurate site performance.
Inputs explained
- Air temperature(F)
- Enter the air temperature in F.
- Altitude(ft)
- Enter the altitude in ft.
Worked example
Using the values the calculator loads with:
Inputs
- Air temperature70 F
- Altitude0 ft
Results
- Air density3.9954 lb/ft3
- Density ratio vs standard53.272
- Barometric pressure29.92 in Hg
- Fan pressure/power correction factor53.272
Frequently asked questions
Does humidity matter?
Slightly — humid air is marginally less dense than dry air at the same temperature, but the effect is small compared to temperature and altitude.
Where is this used?
Correcting fan curves, combustion air calculations and any airflow measurement taken away from standard conditions.
What do I need to enter into the Air Density Correction Calculator?
Just 2 values: air temperature, altitude. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Air Density Correction Calculator work out the answer?
Air density falls with rising temperature and rising altitude, and fan pressure and power scale directly with density. It applies the formula rho = P / (R x T); density ratio vs 0.075 lb/ft3 standard and shows the working so you can check each step by hand.
Is the Air Density Correction Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.