Enter the total roof area and the square feet per drain into the Calculator. The calculator will evaluate the Number of Roof Drains.

## Number of Roof Drains Formula

RD = RA / SFD

Variables:

- RD is the Number of Roof Drains (drains)
- RA (ft^2) is the total roof area
- SFD (ft^2/drain) is the square feet per drain

To calculate the Number of Roof Drains, divide the total roof area by the square footage per drain.

## How to Calculate the Number of Roof Drains?

The following steps outline how to calculate the Number of Roof Drains.

- First, determine the total roof area.
- Next, determine the square feet per drain.
- Next, gather the formula from above = RD = RA / SFD.
- Finally, calculate the Number of Roof Drains.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

total roof area = 5000

square feet per drain = 1000