Siding Calculator
Squares and boxes of vinyl siding from your home's dimensions.
One story is 8 to 10 ft; two stories 17 to 19 ft.
10% standard; 15% for complex walls or diagonal-cut gables.
You need
13.5 squares
Waste included, openings not subtracted (standard practice). Add gable triangles separately.
- Boxes (2 squares each)
- 7 boxes
- Wall area
- 1,224 sq ft
Estimates only. Verify quantities before ordering.
How this is calculated
Wall area = 2 x (length + width) x wall height. Squares = area x (1 + waste) / 100. Boxes assume the common 2-squares-per-box packaging for vinyl siding. Gables are extra: add width x height / 2 for each.
Enter your home's footprint and the wall height from foundation to eaves, and this calculator returns the siding in squares (100 square feet each, the unit siding is sold and quoted in) and the equivalent boxes. Standard practice is not to subtract windows and doors: the offcuts around openings roughly cancel what the openings remove, and the extra is your insurance.
Gable ends add triangles on top of the rectangle this calculator measures. Each gable adds half of (gable width x gable height), so a 30 ft wide gable rising 8 ft adds 120 square feet. Add your gable areas to the calculated total, or fold them into the waste factor for a low-pitch roof.
Siding for common house sizes
Rows assume 10% waste, no opening subtraction, and exclude gables; add width x height / 2 per gable end.
| House | Squares | Boxes |
|---|---|---|
| 24 x 24 ft garage, 9 ft walls | 9.5 squares | 5 boxes |
| 40 x 28 ft ranch, 9 ft walls | 13.5 squares | 7 boxes |
| 48 x 28 ft ranch, 9 ft walls | 15.0 squares | 8 boxes |
| 40 x 28 ft two-story, 18 ft walls | 26.9 squares | 14 boxes |
| 50 x 30 ft two-story, 18 ft walls | 31.7 squares | 16 boxes |
Common questions
What is a square of siding?
One square covers 100 square feet of wall. Vinyl siding is typically packaged two squares per box, and quotes from contractors and suppliers are almost always priced per square, which is why this calculator leads with that number.
Should I subtract windows and doors?
Usually no. The pieces cut away around openings are rarely reusable elsewhere on the wall, so the standard estimating practice is to measure walls as solid rectangles and let openings offset the cutting waste. Subtract only very large areas like a garage door wall.
How do I measure gables?
A gable is a triangle: its area is width times height divided by two. Measure the gable's base width and the vertical rise from the eave line to the peak, halve the product, and add one triangle per gable end. Steep roofs make surprisingly large gables, so measure rather than guess.
How much does the trim add?
J-channel around every opening and edge, starter strip along the bottom, corner posts, and utility trim under windows are all separate purchases, usually sold in 12 ft 6 in lengths. Count linear feet for each: perimeter of openings for J-channel, wall base for starter, and wall height times four for corners.