BTU to CFM Calculator
Airflow from heating or cooling load.
Enter your values
ⓘ Live results
Results
- Required airflow
- 1,667 CFM
- Equivalent tons
- 3
- At 400 CFM/ton
- 1,200 CFM
- In m³/h
- 2,832
Working
- 136,000 / (1.08 x 20) = 1,667 CFM
Quick answer
For air, sensible BTU/h equals 1.08 times CFM times the temperature difference, so CFM = BTU/h / (1.08 x ΔT).
CFM = BTU/h / (1.08 x ΔT)
How to use the BTU to CFM Calculator
- 1Enter the sensible load in BTU per hour (not total load with latent heat).
- 2Enter the design temperature split — 20 °F cooling, 40–70 °F for furnaces.
- 3Use the airflow to size ducts and blower speed.
Worked example
Using the values the calculator loads with:
Inputs
- Sensible load36000 BTU/h
- Temperature difference20 °F
Results
- Required airflow1,667 CFM
- Equivalent tons3
- At 400 CFM/ton1,200 CFM
- In m³/h2,832
- 36,000 / (1.08 x 20) = 1,667 CFM
Frequently asked questions
Where does 1.08 come from?
It bundles air density, specific heat and the 60 minutes per hour into one constant at standard conditions.
Do I use total or sensible BTU?
Sensible only — latent load removes moisture and does not change air temperature.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.