Siding calculator
How many squares of siding your house needs, less windows and doors, with trim and what it typically costs installed.
Siding to order
15 squares
- With 10% waste
- 1,431 sq ft (14.3 sq)
- Area to cover
- 1,301 sq ft
- Walls
- 1,260 sq ft
- Gables
- 225 sq ft
- Openings
- − 184 sq ft
- Starter strip
- 140 ft
- Outside corners
- 36 ft
- Gable rake trim
- 67 ft
- Typical installed vinyl
- $18,682 ($14.36/sq ft)
A square covers 100 sq ft of wall. Typical installed cost is the 2025 national average for replacing siding, trim included; your area and house will differ, so get quotes.
How to calculate siding
Siding is sold and priced by the square: 100 square feet of wall. Add up the walls and gable ends, take out the windows and doors, add extra for cuts and waste, and divide by 100.
- Walls = 2 × (length + width) × wall height
- Each gable = width × gable height ÷ 2, where gable height = width ÷ 2 × pitch ÷ 12
- Area to cover = walls + gables − windows − doors − other openings
- Squares = area × (1 + waste %) ÷ 100, rounded up to order
Worked example
Your 40 × 30 ft house with 9 ft walls has 2 × (40 + 30) × 9 = 1,260 sq ft of wall. At 6/12 each gable is 7.5 ft tall, so the gables add 225 sq ft. Taking out 184 sq ft of windows and doors leaves 1,301 sq ft. With 10% waste that's 1,431 sq ft, or 14.3 squares: order 15 squares.
Typical installed siding cost
From JLC Cost vs. Value 2025, national averages, for replacing 1,250 sq ft of siding, trim included.
| Siding | 1,250 sq ft job | Per sq ft | Per square |
|---|---|---|---|
| Vinyl | $17,950 | $14.36 | $1,436.00 |
| Fiber cement | $21,485 | $17.19 | $1,718.80 |
Siding by house size
For a square one-story house with 9 ft walls and two 6/12 gables, before subtracting windows and doors. Real houses differ, so measure yours above.
| Floor area | Siding area | Squares | Vinyl installed | Fiber cement installed |
|---|---|---|---|---|
| 1,000 sq ft | 1,388 sq ft | 13.9 | $19,938 | $23,864 |
| 1,200 sq ft | 1,547 sq ft | 15.5 | $22,216 | $26,591 |
| 1,500 sq ft | 1,769 sq ft | 17.7 | $25,407 | $30,410 |
| 2,000 sq ft | 2,110 sq ft | 21.1 | $30,299 | $36,266 |
| 2,500 sq ft | 2,425 sq ft | 24.2 | $34,823 | $41,681 |
Siding questions
What is a square of siding?
100 square feet of wall, the same unit roofing uses. Siding is priced and sold by the square, so a house with 1,769 sq ft of wall takes about 17.7 squares before waste.
How much does vinyl siding cost per square foot?
The 2025 national average for replacing 1,250 sq ft of vinyl siding was $17,950, about $14.36 a square foot installed with trim; fiber cement averaged $17.19 a square foot. Prices vary by region, siding style and how much trim the house needs, so get quotes and enter a price per square above to compare.
How much does siding cost for a 2,000 sq ft house?
A square one-story house with 2,000 sq ft of floor has about 2,110 sq ft of wall and gable, so at the typical installed price vinyl comes to about $30,299 and fiber cement about $36,266 before windows and doors. A two-story house of the same floor area has more wall per square foot of floor; enter your own measurements above.
How much extra siding should I order?
The calculator adds the waste percentage you enter for cuts at corners, windows and gables. Walls broken up by many openings, bump-outs or steep gables waste more than long plain walls, so order more for those.
Should I subtract windows and doors?
Yes: the calculator takes them out using the size you enter for each. The defaults (12 sq ft per window, 20 per door) are common rough sizes, not measurements, so measure yours if they're unusual. For a garage door, add its area under "Other openings".