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HVAC & Airflow

Heat Load CFM Calculator

Ventilation needed to remove a watt or BTU heat load.

Enter your values

ⓘ Live results

Results
Airflow required
632 CFM
Heat load
10,236 BTU/h
In kW
3
Equivalent tons
0.85
In m³/h
1,074

Working

  1. 110,236 / (1.08 x 15) = 632 CFM

Quick answer

Airflow to remove heat equals the load in BTU/h divided by 1.08 times the allowable temperature rise.

CFM = BTU/h / (1.08 x ΔT)

How to use the Heat Load CFM Calculator

  1. 1Choose watts or BTU/h and enter the total heat load.
  2. 2Set the temperature rise you can tolerate between intake and exhaust.
  3. 3Size fans for that airflow with headroom for filters and grilles.

Worked example

Using the values the calculator loads with:

Inputs

  • Load unitWatts
  • Heat load3000 W or BTU/h
  • Allowed temperature rise15 °F

Results

  • Airflow required632 CFM
  • Heat load10,236 BTU/h
  • In kW3
  • Equivalent tons0.85
  • In m³/h1,074
  1. 10,236 / (1.08 x 15) = 632 CFM

Frequently asked questions

Why does a smaller ΔT need more air?

The air can only carry so much heat per degree, so a tighter temperature target demands proportionally more airflow.

Is ventilation enough for a server room?

Only if outdoor air is reliably cooler than your target; otherwise you need mechanical cooling.

About this calculator

Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.