Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
Water Usage
Rainwater Harvesting Calculator
Estimate how many litres of rainwater you can collect annually from your roof. Ideal for homeowners and gardeners planning rainwater tanks, irrigation systems, or off-grid water supply.
Fill in the required fields to see your result.
Water Usage
Rainwater Harvesting Calculator
Estimate how many gallons of rainwater your roof can collect annually and what tank size you need to meet your water goals. Useful for sizing cisterns, rain barrels, and off-grid water systems.
Fill in the required fields to see your result.
Key differences
| Rainwater Harvesting Calculator | Rainwater Harvesting Calculator | |
|---|---|---|
| Category | Water Usage | Water Usage |
| Inputs required | 3 | 4 |
| Result | Annual Water Collection (cubic meters) | Annual Rainwater Collection (gallons) |
| What it does | Estimate how many litres of rainwater you can collect annually from your roof. Ideal for homeowners and gardeners planning rainwater tanks, irrigation systems, or off-grid water supply. | Estimate how many gallons of rainwater your roof can collect annually and what tank size you need to meet your water goals. Useful for sizing cisterns, rain barrels, and off-grid water systems. |