Garden irrigation calculator
Convert a garden area and desired water depth into the volume to apply, after effective rain and losses.
Area, rain, desired depth and efficiency are user inputs. This is a volume conversion, not a crop schedule, soil model or weather forecast. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Garden irrigation calculator
- Enter your measured quantities, units and assumptions.
- Review the calculated result and the stated limits.
- Download the report or plan for your project.
Useful next steps
Use one consistent period
Enter the area, the desired depth for a watering period and effective rainfall that already contributes to that target. The result cannot fall below zero when rain exceeds the target.
Allow for application losses
Divide the net water need by your entered efficiency. For example, 20 square metres needing another 15 mm requires 300 litres at the soil, or 375 litres at 80% efficiency.
Save the measurements and assumptions
Download CSV and a text or JSON report. The calculation runs on your device. Changing a unit keeps the number you entered, so check both before using the result.