Enter the total runoff area (ft^2) and the total inches of rainfall (in) into the Runoff Volume Calculator. The calculator will evaluate and display the Runoff Volume.

## Runoff Volume Formula

The following formula is used to calculate the Runoff Volume.

RV = RA * RF/12 / 7.481
• Where RV is the Runoff Volume (gallons)
• RA is the total runoff area (ft^2)
• RF is the total inches of rainfall (in)

## How to Calculate Runoff Volume?

The following example problems outline how to calculate Runoff Volume.

Example Problem #1:

1. First, determine the total runoff area (ft^2).
1. The total runoff area (ft^2) is given as: 50.
2. Next, determine the total inches of rainfall (in).
1. The total inches of rainfall (in) is provided as: 2.
3. Finally, calculate the Runoff Volume using the equation above:

RV = RA * RF/12 / 7.481

The values given above are inserted into the equation below:

RV = 50 * 2/12 / 7.481 = 1.113 (gallons)

Example Problem #2:

The variables needed for this problem are provided below:

total runoff area (ft^2) = 60

total inches of rainfall (in) = 3

Entering these values and solving gives:

RV = RA * RF/12 / 7.481 = 2.01 (gallons)