Compare calculators
Both calculators run independently — change the inputs on either side to compare results.
Water Usage
Rainwater Harvesting Calculator
Estimate how many gallons of rainwater you can collect annually from your roof, capped by your tank size. Use it when designing a rain barrel system or planning irrigation needs.
Fill in the required fields to see your result.
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.
Key differences
| Rainwater Harvesting Calculator | Rainwater Harvesting Calculator | |
|---|---|---|
| Category | Water Usage | Water Usage |
| Inputs required | 4 | 3 |
| Result | Annual Harvestable Water (gallons) | Annual Water Collection (cubic meters) |
| What it does | Estimate how many gallons of rainwater you can collect annually from your roof, capped by your tank size. Use it when designing a rain barrel system or planning irrigation needs. | 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. |