Irrigation Calculator

Calculate irrigation water needed, acre-inches, total gallons, flow rate, runtime, system efficiency, water cost, and energy cost. Use this irrigation calculator for crop water planning, field irrigation schedules, and pump runtime estimates.

Calculate Irrigation Needs

Total Gallons = Field Acres × Water Depth Inches × 27,154 gallons per acre-inch.
Your result will appear here.

How the irrigation calculator works

Water needed:
Enter field acres and target water depth to calculate acre-inches and gallons required.

Irrigation runtime:
Enter flow rate in gallons per minute to estimate how many hours the irrigation set should run.

Required flow rate:
Enter available runtime hours to estimate the required gallons per minute.

Irrigation cost:
Enter water, energy, labor, and other costs to estimate total irrigation cost and cost per acre.

Why use an irrigation calculator?

An irrigation calculator helps estimate how much water is needed and how long a system should run to apply a target water depth.

It can help compare water depth, crop water use, rainfall, system efficiency, flow rate, runtime, total gallons, acre-inches, and irrigation cost.

What your result means

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

Irrigation calculator formulas

Frequently asked questions

How many gallons are in one acre-inch of water?

One acre-inch of water is about 27,154 gallons. This means one inch of water applied over 40 acres is about 1,086,160 gallons.

How do you calculate irrigation water needed?

Multiply field acres by target water depth in inches to get acre-inches, then multiply by 27,154 to estimate total gallons.

How do you calculate irrigation runtime?

Divide total gallons needed by flow rate in gallons per minute, then divide by 60 to convert minutes to hours.

Why does irrigation efficiency matter?

System efficiency accounts for water that does not reach the crop root zone. A less efficient system requires more gross water to meet the same crop water need.