Sprinkler Zone Calculator
How many heads per zone from available GPM and head flow.
Enter your values
ⓘ Live results
Results
- Heads per zone
- 4
- Zones required
- 6
- Zone flow
- 7.2 GPM
- Weekly run time per zone
- 150 minutes
- Split into 3 days
- 50 minutes per session
Working
- 10.75 x 10 GPM / 1.8 = 4 heads per zone
Quick answer
Heads per zone = usable flow (about 75% of available GPM) divided by the flow of one head. Zones = total heads divided by heads per zone.
heads per zone = 0.75 x GPM / GPM per head
How to use the Sprinkler Zone Calculator
- 1Measure available flow by timing how long a 5 gallon bucket takes to fill from an outside tap.
- 2Get GPM per head from the nozzle chart at your operating pressure.
- 3Keep 25% headroom so pressure stays high enough for even coverage.
Worked example
Using the values the calculator loads with:
Inputs
- Available flow10 GPM
- Flow per head1.8 GPM
- Total heads needed24
- Water needed per week1 in
- Precipitation rate0.4 in/hr
Results
- Heads per zone4
- Zones required6
- Zone flow7.2 GPM
- Weekly run time per zone150 minutes
- Split into 3 days50 minutes per session
- 0.75 x 10 GPM / 1.8 = 4 heads per zone
Frequently asked questions
Why not run every head at once?
Flow is shared. Too many heads on one zone drops pressure, the spray falls short and you get dry rings between heads.
How long should each zone run?
Long enough to apply about 1 inch of water per week, split across 2 to 3 sessions so it soaks in instead of running off.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.