What formula does this use?

Flow rate uses the NFPA hydraulic formula Q = 29.83 × C × d² × √NP, where C is the nozzle discharge coefficient (0.97 for smooth-bore, 1.0 for fog), d is tip diameter in inches, and NP is nozzle pressure in PSI.

What is a typical nozzle pressure for smooth-bore tips?

NFPA 13 and NFPA 14 specify 50 PSI residual nozzle pressure for smooth-bore tips on standpipes. Hand-line smooth-bore tips typically use 50 PSI; master stream devices use 80 PSI.

How is friction loss calculated?

Friction loss uses the Hazen-Williams approximation: FL = C_q × Q² × L, where C_q is the hose friction coefficient (typically 2 for 2.5-inch hose), Q is flow in hundreds of GPM, and L is hose length in hundreds of feet.

What is stream reach?

Estimated horizontal stream reach is approximated from nozzle pressure and tip diameter using ballistic trajectory principles. It is a planning estimate; actual reach varies with elevation angle and wind.

What coefficient should I use for a fog nozzle?

Automatic or adjustable fog nozzles are typically rated at a fixed GPM over a pressure range (e.g. 100 GPM at 100 PSI). Use the smooth-bore mode for tip-specific calculations; switch to fog mode and enter rated flow to check supply pressure requirements.

Hose Stream Calculator

Calculate fire hose flow rate (GPM), nozzle pressure, and stream reach from hose diameter and supply pressure.

Hose Stream Inputs

Nozzle Type

Nozzle Tip Diameter (inches)

Common: 0.875, 1.0, 1.125, 1.25, 1.5, 2.0 in

Hose Inlet Pressure (PSI)

Hose Line (for friction loss)

Length (ft)

Diameter (in)

Enter values and press Calculate to see results.

Summary

This calculator uses NFPA-based hydraulic formulas to determine fire hose stream performance. Enter the nozzle diameter and inlet pressure to get flow rate in gallons per minute, actual nozzle pressure, and estimated stream reach. Results help engineers, inspectors, and fire protection planners verify hose stream adequacy for a given hazard class.

How it works

Enter the nozzle (tip) diameter in inches.
Enter the hose inlet (supply) pressure in PSI.
Optionally adjust hose length and diameter to account for friction loss.
The calculator applies the NFPA hydraulic flow formula: Q = 29.83 × C × d² × √P.
Flow rate in GPM, residual nozzle pressure, friction loss, and stream reach are displayed instantly.
Switch between smooth-bore and fog nozzle modes for different coefficient values.

Use cases

Verify hose stream flow meets NFPA 13 or NFPA 14 minimum GPM requirements.
Size supply lines and standpipe risers for multi-story buildings.
Check whether a hydrant can support a single or multiple hose streams.
Estimate stream reach when planning exposure protection layouts.
Evaluate pressure loss over long hose lays during pre-incident planning.
Document hose stream calculations for insurance or code compliance reports.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu