Rainfall is usually expressed in millimeters or inches. With this calculator, you can convert depth units to volumes by multiplying the value with a surface area to get more practical units for other purposes like pump sizing or drainage/canal design. Area input units can also be chosen from a selection.
Enter values, select units and hit “Calculate”
Why is rainfall measured in length (depth) units?
As a standard, you will also stumble upon depth units (mm or in) when looking at historical meteorological data or predictive meteorology like the weather report. The reason is that it has become a standard since anyone can measure it, no matter how big or small their rain gauge is (as long as it doesn't have a wonky bottom like a coke bottle).
When Do Rainfall Units Need Conversion?
Many calculations such as evapotranspiration rely on this data in millimeters, but when trying to calculate water flow or capacity, other units are needed (cubic meters, liters or gallons). This includes calculating certain water consumptions, water flow, piping and pump capacities, rain collector fill-up rate, drainage piping, etc.
This calculator enables you to easily convert one unit to another given your chosen surface area.