This calculator is designed to supply the area of any potential collection surface of any length and width in square feet and/or square inches, based on the length and width values entered in feet and inches, and the potential and estimated actual rainwater recovery in gallons.
Rainwater can be collected from any surface and stored to allow use at a later time for non-drinking water applications such as lawn and flowers. Due to direct loss and other factors, such as evaporation, there is a percentage of the actual potential that is very close for collected water volume. In moist cool areas, that may be in the range of 85% and in dry, hot, desert conditions, it is closer to 60%. Intelligent use of our water, including rainwater, is a responsibility for each of us.