Fire Flow Calculator

Your details

NFA is fastest for field use. Iowa State accounts for ceiling height. ISO adds construction and occupancy risk factors.
Exterior length of the building (or fire compartment).
ft
Exterior width of the building (or fire compartment).
ft
Number of floors actively involved in the fire.
floors
Estimated percentage of the fire area that is actively burning. A room-and-contents fire may be 25-50%; a fully involved floor is 100%.
Upper floors threatened by vertical extension. Each adds 25% of the fire-floor flow, maximum 5.
floors
Adjacent exposed structures threatened by radiated heat. Each adds 25% of the fire building flow.
structures
Target flow rate for each attack hoseline.
Planned suppression duration for water storage planning.
Needed fire flowModerate demand (500-1000 GPM)
800GPM

Required flow rate to control this fire

Needed fire flow3,028L/min
Floor area2,400ft²
Attack lines needed6lines
Backup lines needed6lines
Total hoselines12lines
Water needed24,000gallons
800 GPM
Low<500Moderate500-1000High1000-2500Very high2500+

Needed fire flow: 800 GPM.

  • Using the NFA field formula, this building requires 800 GPM to control the fire.
  • 6 attack lines and 6 backup lines (12 total) are needed based on 150 GPM per line.
  • At 800 GPM for 30 minutes, approximately 24,000 gallons of water will be consumed.

Next stepVerify available hydrant flow with a pitot gauge test before committing resources. Water supply should meet or exceed the calculated needed flow for at least 30 minutes.

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