Rain Barrel Calculator — 公式
## How Rain Collection Is Calculated
One inch of rain on 1 square foot of roof produces about 0.623 gallons of water.
### Formula
**Gallons = Roof Area (sq ft) x Rainfall (in) x 0.623 x Efficiency**
Efficiency accounts for losses from gutters, splashing, and first-flush diverters.
One inch of rain on 1 square foot of roof produces about 0.623 gallons of water.
### Formula
**Gallons = Roof Area (sq ft) x Rainfall (in) x 0.623 x Efficiency**
Efficiency accounts for losses from gutters, splashing, and first-flush diverters.
计算示例
1,500 sq ft roof, 1 inch of rain, 80% collection efficiency.
- Raw collection = 1,500 x 1 x 0.623 = 934.5 gallons
- With 80% efficiency = 934.5 x 0.80 = 747.6 gallons
- Standard barrels = ceil(748 / 55) = 14 barrels