Irrigation Zone Calculator

Calculate the number of sprinkler heads, flow rate, run time, and pipe size for an irrigation zone.

Inputs

Zone Area

sq ft

Water Pressure

PSI

Head Type

Head Spacing

GPM per Head

GPM

Tab to move between fields

Results

Heads Needed

14 heads

Zone Flow Rate

28 GPM

Run Time (1 in/week)45 min

Weekly Water Usage1,246 gal

Pipe Size4 (1=3/4", 2=1", 3=1.25", 4=1.5")

How to Use This Calculator

Enter the total landscape area in square feet to be irrigated.
Set the precipitation rate (in/hr) of your sprinkler or drip system.
Input available water pressure (PSI) and flow rate (GPM) from the meter.
Review zone count, run time per zone, and weekly water schedule.
Program your controller with zone run times based on plant water demand and local ET.

How the result changes with Head Spacing

Head Spacing	Heads Needed	Zone Flow Rate
7.7	34 heads	68 GPM
19	6 heads	12 GPM
34	2 heads	4 GPM
45	1 heads	2 GPM

What each input means

Zone Area: Total area of the irrigation zone to water.
Water Pressure: Static water pressure at the irrigation system connection.
Head Type: 1 = Rotor (20-50 ft radius), 2 = Spray (5-15 ft radius), 3 = Drip.
Head Spacing: Distance between sprinkler heads (head-to-head spacing recommended).
GPM per Head: Gallons per minute per sprinkler head (spray ~1-2 GPM, rotor ~2-6 GPM).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Zone Area = 2000, Water Pressure = 50, Head Type = 2, Head Spacing = 12 = 5 input(s) provided
Calculate Heads Needed
Heads Needed
14 = 14
Calculate Zone Flow Rate
Zone Flow Rate
28 = 28
Calculate Run Time
Run Time
45 = 45
Calculate Weekly Water Usage
Weekly Water Usage
1246 = 1246

Engine last updated August 5, 2026. Checked against 2 independently-derived tests — how we verify calculators.

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