FireCalc – Sprinkler Demand Calculator

Sprinkler Demand Calculator

Estimate remote area demand, elevation and underground losses, and compare against a water supply test. FireCalc is an estimating tool only – confirm all results with the applicable edition of NFPA 13 and a qualified designer.

Inputs

Project information

Project name

Project address

Designer / Company

Job number

Date

Notes

Units

Hazard classification

Density

gpm/ft²

Design area

ft²

Hose allowance

gpm

Max sprinkler spacing (NFPA 13)

Used to estimate number of sprinklers in remote area.

Sprinklers operating (auto, editable)

Calculated from area ÷ spacing. You may override.

Custom spacing X

Custom spacing Y

Sprinkler K-factor (per sprinkler, as shown on datasheet)

Enter exactly as listed on datasheet (typically gpm/√psi per sprinkler).

Elevation difference (supply to sprinklers)

ft (positive = sprinklers above supply)

Underground length

ft (approximate)

Underground C-factor

Used for Hazen–Williams loss estimate.

Static pressure (test)

psi

Residual pressure (test)

psi

Residual flow (test)

gpm

Results

Sprinkler flow–

Hose allowance–

Total demand flow–

Sprinklers operating–

Flow per sprinkler–

Pressure at sprinkler (Pᵒᵖ)–

Elevation loss–

Underground loss–

System demand pressure–

Available pressure at demand flow–

Safety margin at demand–

Supply vs demand–

Notes

• K-factor is used exactly as entered from the sprinkler datasheet (typically in gpm/√psi).
• This tool assumes a single remote area with equal-flow sprinklers using the K-factor entered.
• Elevation and underground losses are approximate and for scoping / review only.
• Always confirm spacing, densities, and design areas against NFPA 13 and local requirements.