Rain Barrel Yield Estimator
Estimate gallons captured from a roof during rain.
Calculate rain barrel yield estimator from clear inputs
Rain Barrel Yield Estimator gives a focused worksheet for home & diy questions where a quick deterministic estimate is more useful than a spreadsheet. The rain barrel yield estimator fields mirror the variables in its formula, and the output separates the main result from supporting values so you can sanity-check this calculation before reusing it.
800 square feet with 1 inch of rain at 85 percent efficiency captures about 423.64 gallons.
Keep the estimate private in your browser
For Rain Barrel Yield Estimator, every calculation runs in your browser with no upload, account, cookie, live lookup, or server-side storage. The rain barrel yield estimator result is best treated as a planning number because the real-world constraints behind this estimate can change the answer. Adjust the rain barrel yield estimator assumptions and confirm important decisions against the relevant source of truth for that exact situation.
Frequently Asked Questions
How much water does an inch of rain produce?
About 0.623 gallons per square foot of roof. An 800 sq ft roof captures a theoretical 498 gallons from 1 inch, or about 424 gallons at 85% efficiency.
What efficiency should I assume?
75 to 90% for metal and shingle roofs, since some water splashes, evaporates, or is lost at the first flush. Rough or gravel roofs capture less.
Should I measure the actual roof surface?
Use the footprint area under the roof (length × width as seen from above), not the sloped surface. Rain falls vertically, so pitch does not increase what you catch.
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