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`A = f( "length" , "width" ,"flat")
`

Enter a value for all fields

The **Surface Area of a Roof** calculator computes the surface area of a roof based on the length, width and the pitch. * Single and Double sided Gabled Roofs *

**INSTRUCTION:** Choose units and enter the following:

**(L)**The length of the area covered by the roof**(W)**The width of the area covered by the roof.**(P)**The pitch of the roof in rise over run**Units**: The default is "system" which will provide the area of the roof. However, the pull-down menu will let you choose 4x8's or bundles of shingles. In these cases, the calculator computes the area and then uses standard sizes to compute the number of 4x8's or bundles of shingles to cover the area.

**Area (A):** This calculator computes area in square feet or other area units, or

- number of 4x8s needed to cover the area
- the number of standard shingle bundles (33.3 ft
^{2}) to cover the area.

The formula works for gabled roofs (two sided) and single sided roofs (see diagram). For gabled roofs, this formula is only accurate if the both gables have the same pitch, which puts the ridge in the middle. For roofs with different pitches, calculate each side separately.