Enter the size of your walls and gables to see how many squares and cartons of vinyl siding to order, along with the starter strip, J-channel and corner posts that go with it.
How to use the vinyl siding calculator
- Add up the length of every wall being sided and enter the total, then the wall height from the bottom of the siding to the eave.
- Enter the number of gable ends and the width and height of one.
- Count the doors and windows. The calculator takes off 21 ft² per door and 15 ft² per window.
- Count the outside and inside corners and keep about 10% for waste.
Formulas
Wall area = total wall length × wall height Gable area = gable width × gable height ÷ 2, per gable Net area = walls + gables − doors × 21 − windows × 15 Squares = net area × (1 + waste %) ÷ 100 Cartons = squares ÷ 2, rounded up Starter strip = total wall length J-channel = 16 ft per window + 17 ft per door + both rakes of every gable
A square is 100 ft² of wall. Most vinyl siding is boxed at two squares per carton, but check the label, because some profiles are packed differently. J-channel goes around every window (all four sides) and door (top and both sides) and along the sloped edges of each gable. Corner posts come in 10 ft lengths, so walls taller than 10 ft need two per corner.
Worked example: a 28 × 42 ft house
- Walls: 140 ft × 9 ft = 1,260 ft².
- Two gables: 2 × (28 × 7 ÷ 2) = 196 ft².
- Openings: 2 doors × 21 + 10 windows × 15 = 192 ft².
- Net area: 1,260 + 196 − 192 = 1,264 ft².
- With 10% waste: 1,390 ft², which is 13.9 squares or 7 cartons.
- Starter strip: 140 ÷ 12 = 12 pieces. J-channel: 160 + 34 + 63 = 257 ft, or 21 pieces.
Questions
How many squares of siding do I need for a 1,500 sq ft house?
Floor area does not give the wall area directly. A single-story 1,500 ft² house typically has 1,300 to 1,600 ft² of wall after openings, so 15 to 18 squares with waste. Measure the walls to be sure.
How much waste should I allow for vinyl siding?
10% suits a simple rectangular house. Allow 15% when there are many gables, dormers or windows, because each one adds angled or short cuts.
How many pieces are in a square of vinyl siding?
It depends on the profile. A common 12 ft double 4 in panel covers 8 ft², so about 12.5 panels make a square; a double 5 in panel covers 10 ft², so 10 panels make a square.