Sprinkler System Design Calculator

Calculate precipitation rate, head count, zone sizing, and run times for sprinkler irrigation systems.

Lawn area (sq ft)

Head spacing (ft)

Row spacing (ft)

GPM per head

Target application (in)

Available flow (GPM)

Tab to move between fields

Precip rate (in/hr)

1.07

Run time per zone (min)

Total heads needed23

Total system GPM57.5

Zones needed5

Heads per zone5

Total watering time (min)140

Weekly water use (gal)4,836

Gpm Per Zone12.5

Coverage Ratio (%)100%

How to Use This Calculator

Enter total lawn or field area in square feet.
Set head spacing and row spacing in feet — use head-to-head spacing for best uniformity.
Enter GPM per head and your available source flow in GPM.
Set target application depth in inches per irrigation event.
Review Precipitation rate (in/hr), Run time per zone (min), and Zones needed to design and program your controller.

How the result changes with Head spacing (ft)

Lawn area (sq ft): Total area to irrigate in square feet.
Head spacing (ft): Distance between sprinkler heads. Use head-to-head spacing for best uniformity.
Row spacing (ft): Distance between rows of sprinkler heads.
GPM per head: Flow rate per sprinkler head. Spray heads: 0.5-3 GPM. Rotors: 2-8 GPM.
Target application (in): Desired water depth per irrigation event.
Available flow (GPM): Flow rate available from water meter or source.

Precip rate (in/hr): Sprinkler precipitation rate = 96.3 × GPM / (head spacing × row spacing).
Run time per zone (min): Minutes each zone must run to apply target depth.
Total heads needed: Number of sprinkler heads for full coverage.
Total system GPM: Flow if all heads run simultaneously.
Zones needed: Minimum zones to stay within available flow.
Heads per zone: Sprinkler heads per zone.
Total watering time (min): Total time to water all zones sequentially.
Weekly water use (gal): Estimated weekly usage at 3 waterings per week.

Identify Input Parameters
4 parameters
Lawn area (sq ft) = 5000, Head spacing (ft) = 15, Row spacing (ft) = 15, GPM per head = 2.5 = 6 input(s) provided
Calculate Precip rate
Precip rate = (96.3 * gpmPerHead) / (headSpacingFt * rowSpacingFt)
1.07 = 1.07
Calculate Run time per zone
Run time per zone = (targetApplicationIn / precipRateInPerHr) * 60
28 = 28
Calculate Total heads needed
Total heads needed
23 = 23
Calculate Total system GPM
Total system GPM = totalHeads * gpmPerHead
57.5 = 57.5