Rainwater Harvest
Use the Rainwater Harvest. Enter Roof area (sq ft) and Rainfall (inches) for a clear result, formula explanation, and practical planning checks.
Rainwater Harvest measurements
Enter your values, then calculate.
Result
How to calculate rainwater harvest
This calculator estimates total rainwater harvest volume from roof area and rainfall amount, using a standard collection conversion factor.
How the calculation works
Harvest volume = Roof area × Rainfall × 0.623.
Example
1,200 sq ft roof, 2 inches of rain: 1,200×2×0.623 ≈ 1,495 gallons.
Frequently asked questions
How is Result calculated?
Result = [Roof area] × [Rainfall] × 0.623.
Is the Rainwater Harvest free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Rainwater Harvest
Harvest volume = Roof area × Rainfall × 0.623.
Let's understand your rainwater harvest result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Rainwater Harvest
- This calculates theoretical maximum collection — real-world systems lose some water to evaporation, overflow, and first-flush diversion.
- Multiply by your area's average annual rainfall for a rough annual harvest potential estimate, useful for sizing a storage system.
Common Rainwater Harvest Mistakes to Avoid
- Treating this theoretical maximum as the actual expected collection, without accounting for real-world losses in an actual system.
When to Use This Calculator
This calculator estimates total rainwater harvest volume from roof area and rainfall amount, using a standard collection conversion factor.