Fire Sprinkler Demand Calculator

Size up your demand before you draw a thing. Enter the basics and it lays out a representative system and runs a real hydraulic pass to estimate the GPM and PSI you'll need at the source.

What it does

This is a feasibility check grounded in actual hydraulics, not a rule of thumb. Behind the scenes it builds a representative tree system and solves it:

• Density/area demand per NFPA 13
• Hazen-Williams pipe friction loss
• Elevation and backflow-preventer losses
• K-factor start pressure and hose stream allowance
• A flag on whether your water supply looks adequate

How to use it

1. Enter the building dimensions and hazard classification.
2. Pick your main, branch, and underground pipe.
3. Read the estimated GPM and PSI demand, and the supply-adequacy flag.

FAQ

How accurate is a preliminary demand calc?

It is an early estimate for feasibility and bidding, not a stamped hydraulic calculation. It runs a real hydraulic pass on a representative layout so it is far closer than a rule of thumb, but your final design governs.

What is the density/area method?

NFPA 13 defines a design density in gpm per square foot applied over a design area for each hazard classification. The demand is the flow and pressure needed to deliver that density over the most remote area, plus hose streams.

Does it include hose stream allowance?

Yes. The estimate adds the hose stream allowance for the selected hazard so the demand reflects the total at the source.