Siding Calculator
Squares and boxes of siding from wall area minus openings.
Enter your values
Enter the perimeter of house in ft.
Enter the wall height in ft.
Enter the gable area in sq ft.
Enter the window and door area in sq ft.
Enter the waste in %.
Enter the cost per square in $.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Siding squares
- 14.19
- Net wall area
- 1,290 sq ft
- Boxes (2 squares each)
- 8
- Starter strip
- 150 ft
- J-channel
- 322 ft (estimate)
- Material cost
- $3,263.70
Working
- 1150 x 9 + 120 - 180 = 1,290 ft2 -> 14.19 squares
Quick answer
Siding area = wall area minus openings, plus waste. One square covers 100 sq ft; vinyl usually ships two squares per box.
squares = (wall area - openings) x (1 + waste) / 100
At a glance
| What it does | Squares and boxes of siding from wall area minus openings. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Perimeter of house, Wall height, Gable area, Window and door area, Waste, Cost per square |
| Main output | Siding squares |
| Formula | squares = (wall area - openings) x (1 + waste) / 100 |
| Cost | Free — no sign-up, no download |
How to use the Siding Calculator
- 1Walk the perimeter and measure the wall height to the soffit.
- 2Add gable triangles (base x height / 2 each) and subtract windows and doors.
- 3Add 10% waste, more if the house has many corners and dormers.
Inputs explained
- Perimeter of house(ft)
- Enter the perimeter of house in ft.
- Wall height(ft)
- Enter the wall height in ft.
- Gable area(sq ft)
- Enter the gable area in sq ft.
- Window and door area(sq ft)
- Enter the window and door area in sq ft.
- Waste(%)
- Enter the waste in %.
- Cost per square($)
- Enter the cost per square in $.
Worked example
Using the values the calculator loads with:
Inputs
- Perimeter of house150 ft
- Wall height9 ft
- Gable area120 sq ft
- Window and door area180 sq ft
- Waste10 %
- Cost per square230 $
Results
- Siding squares14.19
- Net wall area1,290 sq ft
- Boxes (2 squares each)8
- Starter strip150 ft
- J-channel322 ft (estimate)
- Material cost$3,263.70
- 150 x 9 + 120 - 180 = 1,290 ft2 -> 14.19 squares
Frequently asked questions
Should I subtract every window?
Subtract anything larger than about 10 sq ft. Leaving small openings in the total covers the offcuts you will lose around them anyway.
How much extra should I order?
10% on a simple box-shaped house, up to 15 to 20% on a complex facade with dormers, bays and steep gables.
What do I need to enter into the Siding Calculator?
Just 6 values: perimeter of house, wall height, gable area, window and door area, waste, cost per square. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Siding Calculator work out the answer?
Siding area = wall area minus openings, plus waste. One square covers 100 sq ft; vinyl usually ships two squares per box. It applies the formula squares = (wall area - openings) x (1 + waste) / 100 and shows the working so you can check each step by hand.
Is the Siding Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.