Fire Flow Calculator

Add if adjacent structures at risk
NFA Fire Flow (pre-plan estimate)

Fire Flow Calculator (NFA Method)

Fire Flow Calculator – Estimate Water Demand for Firefighting

The Fire Flow Calculator helps you estimate the amount of water needed to fight a fire in a building. It uses the NFA formula:

Fire Flow (GPM) = (Length × Width) ÷ 3 × % Involvement
+25% if exposures are present

This method is widely used in pre-fire planning by fire departments in the U.S. and internationally. It provides a quick, simple way to estimate fire suppression water flow.

🔧 How to Use:

  1. Select your preferred unit (Feet or Meters).

  2. Enter the building Length (L) and Width (W).

  3. Enter the percentage involvement (how much of the structure is burning).

  4. Tick the box if there are exposures (nearby buildings at risk).

  5. The calculator will display results in GPM (gallons per minute) and LPM (liters per minute).

Note: This is for educational and planning purposes only. Always confirm with NFPA, ISO, or your Authority Having Jurisdiction (AHJ).