Fire Hose Friction Loss

Friction loss through a hose lay, from its diameter, length, and flow.

Run the calculator

Example

You enter

Hose diameter 2.5_in
Flow (gpm) 250
Length (ft) 200

You get

Friction loss 25 psi

Checked against published worked examples from: National Fire Academy.

Details, formula, and sources

ScopeCQ^2L formula by hose diameter, length, GPM.

Formula or tableFL = C × (Q/100)² × (L/100), FL in psi, Q in gpm, L in ft; C per hose diameter from NFA training tables (1.75 in, 2.5 in, 3 in, 4 in, 5 in, etc.).

Source and editionNational Fire Academy hose-hydraulics training materials (U.S. government, public domain).

Free accessFree at usfa.fema.gov/training.

What governsEstimate. AHJ and licensed fire protection engineer govern.

API field nameshose_diameter, gpm, length_ft, friction_loss_psi

C-value table data/fire/hose-friction.json keyed to hose diameterNFA training materials