What it calculates
Estimate sprinkler zones from available flow and head demand.
Irrigation Zone Calculator
Estimate sprinkler zones from available flow and average head demand.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
Landscape estimating
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. Enter the flow of the selected heads at the actual operating pressure.
How the calculation works
Available flow is reduced by the reserve percentage, then divided by average sprinkler demand to estimate heads per zone.
What the result means
Hydraulic design also depends on pressure, pipe size, elevation, nozzle selection and manufacturer data.
Work within the entered flow budget
With 10 GPM available and a 20% reserve, usable flow is 8 GPM. If each identical head uses 2 GPM, the model allows 4 heads per zone. Ten heads divided by 4 rounds up to 3 zones.
Contractor tip: Enter the flow of the selected heads at the actual operating pressure. Do not treat the forced minimum of one head as evidence that an undersupplied system can support it.
Verify the final quantity
This is only a flow-budget calculation. It does not calculate pressure at the heads, pipe friction, elevation, coverage, precipitation rate or mixed nozzle demand. A zone still needs enough flow for at least one head.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.