Siding Calculator
This siding calculator finds how much siding a house needs from the total wall length, wall height, door and window area, and a waste allowance. Enter them and the siding calculator returns the siding area in square metres and square feet, and the number of siding squares to order. It works for vinyl, fibre cement, and lap siding.
Results
The Siding Calculator is part of our Materials Estimating collection. Browse more materials estimating to size, convert, and check your work alongside this tool.
What the siding calculator shows
Siding is sold by the square, which is 100 square feet of wall coverage. The siding calculator works out the net wall area, removes doors and windows, adds waste for cuts and overlaps, and converts the result into squares. Whether you are figuring siding for a whole house or one wall, the method is the same.
Figuring siding square footage
Figuring siding square footage takes the gross wall area, removes openings, adds waste, and converts to squares:
One square metre is 10.764 square feet, so the siding square footage calculator converts before dividing by 100.
Siding estimate calculator example
40 m of wall at 2.7 m high, 12 m² of doors and windows, and 10 percent waste. The siding estimate calculator gives:
So order 12 squares of siding plus the trim and accessories.
How to use the vinyl siding calculator
Enter the total length of the walls to be clad, the wall height, the combined area of doors and windows, and a waste allowance. The vinyl siding calculator returns the siding area and the squares to buy. Use 10 percent waste for a simple house and 15 percent for many corners, dormers, or a complex roofline. Measure gable triangles separately and add them as extra area.
Reading the siding square footage calculator result
The squares figure is the siding panels to order; trim pieces such as J-channel, corner posts, starter strip, and soffit are counted separately by length. Buy a little extra from the same production lot, since colour can shift between batches. The siding square footage calculator assumes flat walls; add gables, dormers, and bay walls as extra area before you estimate siding square footage.
When estimating siding
- Pricing a re-siding job with the siding estimate calculator
- Ordering vinyl with the vinyl siding material calculator
- Comparing lap, board and batten, and fibre cement
- Budgeting a new build exterior
Common siding calculator mistakes
- Forgetting gables. Add triangle areas for gable ends.
- Too little waste. Complex walls need 15 percent, not 5.
- Ignoring trim. Corners and J-channel are ordered separately.
Tips for accurate results
- Measure each wall at its widest and tallest point.
- Order from one production lot for colour match.
- Keep a box of spares for future repairs.
Figure vinyl siding for gables and dormers
Gable ends are triangles, so their area is half the base times the height. Add each gable and dormer face to the wall area before you figure vinyl siding, since these shapes produce more cut waste than flat walls. Houses with many angles justify 15 percent waste. If part of the exterior will be painted rather than clad, the paint calculator handles those areas.
Lap siding calculator vs panel siding
A lap siding calculator uses the same area method, but board width and exposure decide how many boards a square needs. Panel siding, such as vinyl double-four, already lists coverage per carton, so you divide the area by that coverage. In both cases the squares figure from this tool is the starting point for the order.
Siding calculator reference (10% waste)
| Net wall area | With waste | Squares |
|---|---|---|
| 50 m² | 592 ft² | 6 |
| 75 m² | 888 ft² | 9 |
| 96 m² | 1,137 ft² | 12 |
| 150 m² | 1,776 ft² | 18 |
Siding Calculator FAQ
What is a square of siding?
A square is 100 square feet of wall coverage, about 9.29 m². Siding is ordered by the square.
How do you figure vinyl siding?
Multiply wall length by height, subtract doors and windows, add 10 to 15 percent waste, and divide the square feet by 100.
Should I subtract windows?
Yes, subtract large openings. Many installers leave small windows in as a built-in waste margin.
Does the calculator include trim?
No. Count starter strip, J-channel, corners, and soffit separately by length.