Rain Barrel & Roof Catchment Water Calculator
Calculate annual rainwater harvesting potential in gallons and cubic meters from roof area, precipitation depth, and runoff efficiency.
- 100% free
- Private in browser
- No signup
- No watermarks
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About Rain Barrel & Roof Catchment Water Calculator
Calculate annual rainwater harvesting potential in gallons and cubic meters from roof area, precipitation depth, and runoff efficiency. Enter Catchment Roof Area, Average Annual Rainfall and Runoff Efficiency Factor and the tool works out Total Annual Yield, Yield per 1-Inch Storm and Barrels Filled per 1-Inch Storm straight away. Everything runs in your browser, so your data never leaves your device.
How to use Rain Barrel & Roof Catchment Water Calculator
- Enter Catchment Roof Area, Average Annual Rainfall and Runoff Efficiency Factor.
- Adjust the remaining options (Rain Barrel Capacity) to match your case.
- Read Total Annual Yield, Yield per 1-Inch Storm and Barrels Filled per 1-Inch Storm in the results panel — copy or download what you need.
Key features
- Shows Total Annual Yield (Gallons)
- Shows Yield per 1-Inch Storm (Gallons)
- Shows Barrels Filled per 1-Inch Storm
- 4 adjustable inputs, results update as you type
- No signup, no limits
Frequently asked questions
- Is this calculation free and private?
- Yes, 100% of calculations execute locally in your web browser. No inputs or personal data are stored or transmitted.
- What does the Rain Barrel & Roof Catchment Water Calculator give me?
- It works out Total Annual Yield, Yield per 1-Inch Storm, Barrels Filled per 1-Inch Storm and Total Harvest, updating live as you change the inputs.
- What do I need to enter?
- Just Catchment Roof Area, Average Annual Rainfall, Runoff Efficiency Factor and Rain Barrel Capacity. Every field has a sensible default you can start from.
- Is my data uploaded anywhere?
- No. The calculation runs in your browser with JavaScript — nothing you type is sent to a server or stored.
- Does it work on a phone?
- Yes. The layout adapts to small screens and needs no app or signup.
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