Irrigation Water Calculator
Calculate irrigation volume and pumping time for a given application depth.
What this page needs from you
This page asks for area in acres, water depth to apply in inch, system efficiency as a percentage and available flow in gpm. From those it returns water needed in gallons, together with acre-inches, hours of pumping, in cubic metres and per acre. Every figure updates as you type, and nothing you enter leaves your browser.
Rates are regional, and local advice beats a general figure
Soil type, rainfall, variety and season change the right answer more than the arithmetic does. Use this to plan and to check an order, and check the figure against your local extension service, agronomist or supplier before committing to a whole field.
The formula
One acre-inch = 27,154 gallons; divide by system efficiency for gross application
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the Irrigation Water Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
Irrigation Water Calculator — frequently asked questions
Is this irrigation water calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
This page answers each of these searches. They are the exact phrases visitors use to find the irrigation water calculator.
- irrigation water calculator
- gallons per acre irrigation
- irrigation requirement calculator
- how much water to irrigate
- acre inch water
About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed September 14, 2026 · Calculation runs client-side · No data collected · Report an error