Rainfall Volume Table: Water volume by Catchment area
Reference table of water volume for Rainfall Volume across a range of catchment area values — exact, engine-computed figures you can read off at a glance.
Rainfall Volume Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Water volume
2,500.0
- In cubic metres
- 2.500
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Rainfall Volume Calculator
The Rainfall Volume Calculator works out your water volume, along with 1 related figure in an instant. Enter catchment area, rainfall depth and collection efficiency and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the catchment area.
- Enter the rainfall depth.
- Enter the collection efficiency.
- Read off your water volume, together with in cubic metres — the calculator updates automatically, with no button to press.
Formula
The Rainfall Volume Calculator uses the formula:
Water volume = Catchment area × Rainfall depth × Collection efficiency ÷ 100
Worked example
For example, with catchment area of 100 m², rainfall depth of 25 mm and collection efficiency of 1%, the water volume is 2,500.0.
| Catchment area | 100 m² |
|---|---|
| Rainfall depth | 25 mm |
| Collection efficiency | 1% |
| Water volume | 2,500.0 |
|---|---|
| In cubic metres | 2.500 |
Results are estimates for educational use, not professional advice.
Key terms explained
- Volume
- The amount of three-dimensional space an object occupies, measured in cubic units.
- Area
- The amount of two-dimensional space a shape covers, measured in square units.
Frequently asked questions
Multiply the area in square metres by the rainfall in millimetres. 1 mm over 1 m² is 1 litre, so 25 mm over 100 m² is 2,500 litres.
It is the fraction of rain actually captured, after losses from splash, evaporation and overflow. Set it below 100% for real roofs.
It estimates how much water a roof can collect from a storm, helping size tanks and gutters.
Exactly 1,000 litres make one cubic metre of water.
Enter the catchment area. Enter the rainfall depth. Enter the collection efficiency. Read off your water volume, together with in cubic metres — the calculator updates automatically, with no button to press.
Related guides
How to Calculate Rainfall Volume: Formula, Steps & Examples
Learn how to calculate Rainfall Volume — the formula explained step by step, with worked examples and a free calculator to check your answer.