Default (4) K4.9 residential heads at 13 gpm each. Extended-coverage heads (e.g. 20×20) flow more — raise the flow per head (≈20 gpm).
Storage CMDA/CMSA density/area. Not sure of the criteria? Use the Storage Analysis tool to find your required demand.
ESFR/FM storage — (n) heads at a K-factor and pressure. Not sure? Use the Storage Analysis tool.
Building footprint, height to the highest sprinkler, and the design basis. Pressure is sized for a max-spaced sprinkler (worst case).
Tree = single feed main with dead-end branch lines. Grid = branch lines fed from two parallel mains (lower friction, demand near theoretical).
Underground is optional — leave the size at “none” if there's no supply lateral to include.
Advanced assumptions
C=120 (black steel). K-factor is auto-selected so the starting head pressure lands near 7 psi — edit to override.
Enter a flow test to check whether the supply meets the demand and get a preliminary pump recommendation. Skip if unknown.
Full pipe-network solve (Newton-Raphson nodal balance) — builds every cross main, branch line and operating head and disperses the flow across the whole grid, like a real hydraulic engine. Runs automatically; validated against AutoSPRINK reference calcs (±4%).
Preliminary estimating / feasibility tool only. Early theoretical demand from simplified, calibrated assumptions (idealized tree/grid geometry, density/area design point, chart-derived backflow loss). It does not replace a full NFPA 13 hydraulic calculation or engineering review.