How it works
Fill in the 2 fields above and Rainwater Harvesting Calculator calculates the result instantly, recalculating as you change any value. It applies the formula gallons = area × inches × 0.623. The math runs locally in your browser — nothing is sent to a server.
Formula
gallons = area × inches × 0.623Examples
- Roof area 1000 sq ft, Rainfall 1 in → Water collected: 623 gallons
Frequently asked questions
How do I use the Rainwater Harvesting Calculator?
Enter your values in the 2 input fields and the result is calculated automatically as you type. Change any value to see the numbers update instantly.
What formula does the Rainwater Harvesting Calculator use?
It uses gallons = area × inches × 0.623. The calculation is performed in your browser using standard, well-established math for accurate results.
Is my data private?
Yes. The Rainwater Harvesting Calculator runs entirely in your browser. Nothing you enter is uploaded, saved to a server, or shared — it never leaves your device.
Is the Rainwater Harvesting Calculator free?
Yes, it is completely free with no sign-up, no limits and no watermarks. Like every tool on environment and the rest of the platform, you can use it as often as you like.
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