Irrigation Flow Rate Calculator

Calculate irrigation flow rate, required GPM, GPM per acre, runtime, water depth, total gallons, acre-inches, and irrigation cost. Use this calculator for center pivots, sprinklers, drip irrigation, flood irrigation, and field water planning.

Calculate Irrigation Flow Rate

Required GPM = Target Gallons ÷ Runtime Hours ÷ 60.
Your result will appear here.

How the irrigation flow rate calculator works

Required flow rate:
Enter acres, target water depth, available runtime, and efficiency to estimate required gallons per minute.

Runtime from flow rate:
Enter a known GPM to estimate how long the system should run.

Water depth applied:
Enter known GPM and runtime to estimate gross and net water depth applied.

Irrigation cost:
The calculator estimates water, energy, labor, setup cost, total cost, and cost per acre.

Why use an irrigation flow rate calculator?

An irrigation flow rate calculator helps estimate whether a pump or irrigation system has enough capacity to apply the desired water depth in the available time.

It can help compare field acres, target depth, system efficiency, known GPM, required GPM, runtime, total gallons, and irrigation cost.

What your result means

Your result shows estimated required flow rate, GPM per acre, runtime hours, runtime days, gross water depth, net water depth, total gallons, acre-inches, acre-feet, and irrigation cost. These are estimates based on the values you enter.

Irrigation flow rate formulas

Frequently asked questions

How do you calculate irrigation flow rate?

Calculate the total gallons needed, then divide by the available runtime hours and divide by 60. This gives the required gallons per minute.

How do you calculate GPM per acre?

Divide total irrigation flow rate by field acres. For example, 800 GPM across 40 acres equals 20 GPM per acre.

How many gallons are in an acre-inch?

One acre-inch is about 27,154 gallons. That is the water volume needed to cover one acre with one inch of water.

Why does efficiency increase required GPM?

If some pumped water is lost to evaporation, wind drift, runoff, or poor distribution, the system must pump more gross water to deliver the desired net water depth.