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.

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## 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:

- First, determine the total runoff area (ft^2).
- The total runoff area (ft^2) is given as: 50.

- Next, determine the total inches of rainfall (in).
- The total inches of rainfall (in) is provided as: 2.

- 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)