Siding Calculator
Two 40×10 walls, two 24×10 walls, and two gables 40 ft wide by 8 ft high, minus 90 ft² of openings, are 1,510.00 ft². At 10% waste that is 1,661.00 ft², 16.61 squares, and 9 boxes at the example 200 ft² coverage.
Last updated . Two rectangles open the form, plus one gable group and two opening groups. Waste starts at 10. Coverage starts at 200, marked as an example.
A siding calculator for wall rectangles plus gable triangles, minus the openings you type, plus a waste percent. Squares are the order area divided by 100. Boxes use the coverage you type.
Paper inside: wallpaper calculator. Battens on a wall: board and batten calculator. The roof above the gable: roofing calculator.
Siding area
Wall rectangle 1
Wall rectangle 2
Gable triangle
Opening 1
Opening 2
200 is an example so the box count can be checked. Type the coverage printed on your box. It is not a product size.
Each gable is ½ × width × rise, the triangle above a wall, not a second copy of that wall. Openings are rectangles subtracted after the walls and gables are added. Waste opens at 10 so offcuts have a cushion. Type the percent you want.
Results
How the siding area is calculated
Wall area is each rectangle’s width × height × count. Gable area is ½ × width × rise × count. Opening area is each opening’s width × height × count. Net = walls + gables − openings. Order = net × (1 + waste ÷ 100). Squares = order ÷ 100. Boxes = ceil(order ÷ coverage) when you type a coverage greater than zero, and “Enter a coverage” when that box is empty or not positive.
The 2022 Vinyl Siding Installation Manual, in its how-to-measure section, says every 100 square feet (9.29 square meters) is called a square for ordering, draws a gable as ½ × height × width, and tells you to add 10 percent to the material estimate. It also says ordinary windows and doors are not usually deducted. This form lets you deduct them and still type a waste percent, which is a different choice. The manual is the source for the square and for the gable triangle, not a claim that 200 square feet is anyone’s box.
Source: 2022 Vinyl Siding Installation Manual (Polymeric Exteriors), “How to measure,” including the square sentence, the gable figure, and the 10 percent note at the estimating worksheet. No price is shown. Starter, J-channel, and corners are not counted.
Order for the opening house
| Case | Net | Order | Squares | Boxes |
|---|---|---|---|---|
| 10% waste, example 200 ft² | 1,510.00 ft² | 1,661.00 ft² | 16.61 | 9 |
| 0% waste, example 200 ft² | 1,510.00 ft² | 1,510.00 ft² | 15.10 | 8 |
| 10% waste, coverage cleared | 1,510.00 ft² | 1,661.00 ft² | 16.61 | Enter a coverage |
Worked example
Leave both wall pairs, both gables, both opening groups, waste at 10, and coverage at 200. With waste reads 1,661.00 ft². Squares reads 16.61. Boxes reads 9. Replace 200 with the coverage printed on the box before you order.
Siding questions
How many squares of siding is this house?
Leave wall 1 at 40 ft by 10 ft, count 2; wall 2 at 24 ft by 10 ft, count 2; the gable at 40 ft wide and 8 ft of rise, count 2; opening 1 at 3 ft by 7 ft, count 2; opening 2 at 3 ft by 4 ft, count 4; waste at 10; coverage at 200. Walls read 1,280.00 ft². Gables read 320.00 ft². Openings read 90.00 ft². Net reads 1,510.00 ft². With waste reads 1,661.00 ft². Squares reads 16.61. Boxes reads 9.
Where do 1,280, 320, and 90 come from?
Walls are 2 × 40 × 10 + 2 × 24 × 10 = 800 + 480 = 1,280.00 ft². Each gable is half of 40 × 8, and two of them are 320.00 ft². Openings are 2 × 3 × 7 + 4 × 3 × 4 = 42 + 48 = 90.00 ft². Net is 1,280 + 320 − 90 = 1,510.00 ft². The gable is the triangle above the wall, not a second copy of the rectangle.
Why 16.61 squares and 9 boxes?
Ten percent waste makes the order 1,510 × 1.1 = 1,661.00 ft². Squares are that order divided by 100, so 16.61. The coverage box opens at 200. 1,661 ÷ 200 = 8.305, which rounds up to 9 boxes. The 2022 Vinyl Siding Installation Manual calls every 100 square feet a square for ordering. The 200 in the box is an example coverage so the box line can be checked, not a carton size.
What changes when waste is 0?
Set waste to 0 and leave coverage at 200. Net stays 1,510.00 ft². With waste reads 1,510.00 ft². Squares reads 15.10. Boxes reads 8, because 1,510 ÷ 200 = 7.55 and that rounds up. The 10 in the waste box is a starting allowance for offcuts. The manual’s worksheet says to add 10 percent, and you can type a different percent.
What if the coverage box is cleared?
Clear the coverage box, or type 0. Walls, gables, openings, net, the waste area, and squares still show. Boxes reads Enter a coverage. An empty coverage is not treated as a product size.
Should windows stay in the area?
The 2022 Vinyl Siding Installation Manual says windows and doors are not usually deducted, and that leaving them in supplies an allowance, while a very large opening such as a garage door can be deducted. This form subtracts every opening you type, then applies the waste percent on its own. Leave an opening count at 0 if you want that opening to stay in the area. Doing both a deduction and a large waste percent counts the offcut twice.
What if the openings swallow the walls?
Set both wall counts to 0 and leave the gable count at 0. Every result line reads —. The note reads: Openings are at least as large as the walls and gables, so nothing is left to side. A negative waste percent reads: Enter a waste percent of zero or more.