Please ensure Javascript is enabled for purposes of accessibility estimating installing vinyl siding Skip to main content

Mega Menu

Estimating Installing Vinyl Siding


These formulas apply for both horizontal and vertical installations.  
NOTE: When estimating for a large project, you may want to add a waster allowance of 10 percent to the totals for siding, soffit and accessories.  
Read about completion here

Rectangular wall surfaces

Measure height (excluding gables). Measure width  
(including doors and windows).

_____________ x _____________ = _____________  
(height) (width) (surface area)

Repeat for remaining walls.

Triangular gable end surfaces

Measure height at center (add 1' to allow for waste).

Measure width and divide by half.

(height) (1/2 width) (surface area)

Repeat for remaining gables.

NOTE: Lower pitch roofs will produce more waste than higher pitch roofs.

Discover here the Vinyl Siding Terminology

Upper wall of gambrel house

Divide the upper wall of a gambrel house as shown in the illustration. Then use the following formulas:

1/2 (B + C) x H = ___________

1/2 C x D = ____________

Add these figures to get total area: ____________

Repeat for remaining gambrel surfaces.

Dormer sides

Measure height of dormer (add 1' to allow for waste).

Use the following formula:

_____________ x _____________ = ____________________  
(1/2 height) (1/2 width) (surface area, 1 side)

____________________ x 2 = _________________________       
(surface area, 1 side) (total dormer surface area)

Repeat for all dormers.


Measure width of eave to be covered. Measure length of eave.

_____________ x _____________ = _____________       
(width) (length) (surface area)

Repeat for remaining eaves.

Porch Ceiling  

Measure length of porch area to be covered and width of porch.

_____________ x _____________ = _____________       
(length) (width) (surface area)

Find here all the equipment and tools for vinyl siding installation