Siding Calculator
Estimate siding cartons from wall areas, openings and the coverage on each carton.
Last reviewed September 19, 2026
Result
Enter wall areas to see the result.
https://calcgallery.com/paint-drywall/siding-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Add every rectangular wall or wall section separately.
- Enter the combined area of windows and doors to subtract.
- Enter the usable coverage printed on one carton of the exact siding.
- Add a custom allowance for cuts and read the whole-carton quantity.
How it is calculated
The wall rectangles are summed, measured openings are removed, and the result is divided by the coverage of the product you will buy:
Net area = sum of wall rectangles − openings
Order area = net area × (1 + allowance)
Cartons = ceil(order area ÷ coverage per carton)The carton count rounds upward because a partial carton cannot complete the last course.
Planning the order
Measure elevations separately. Gables and other non-rectangular parts can be split into simpler shapes with the square-footage calculator, then entered as equivalent rectangles here.
Use installed coverage. Laps and overlaps mean the face width is often less than the physical board or panel width. The labelled coverage handles that difference.
Count accessories from the layout. Corners, openings and transitions drive the accessory order and cannot be inferred from square area alone.
Keep batches together. Colour and texture can vary. Order the main job and reasonable repair stock from the same production batch when possible.
With your numbers
- Net siding = 700 ft² − 100 ft² = 600 ft²
- With 0% extra = 600 ft²
- That area ÷ 100 ft² per carton, rounded up to 6 cartons
Quick reference
No extra is added by default. Use Custom for end cuts, gables, corners and the layout of the chosen siding system.
| Job | Siding cartons to buy |
|---|---|
| 600 ft² net, 100 ft² cartons | 6 |
| Two walls with 100 ft² openings | 6 |
| 1,200 ft² net, 200 ft² cartons | 6 |
| Four 30 × 9 ft walls | 10 |
| 60 m² net, 10 m² cartons | 6 |
| Two metric walls with openings | 6 |
Common questions
- How many siding cartons cover 600 square feet?
- At 100 ft² per carton, 600 ft² takes 6 cartons with no allowance. A 10% allowance makes 660 ft², which rounds up to 7 cartons.
- Should I subtract windows and doors?
- Subtract their measured area, but remember that openings also create end cuts. Use the custom allowance to account for the actual layout.
- Does this include siding accessories?
- No. Starter strip, corner posts, channels, trim, fasteners and flashing depend on the chosen system and must be counted from the elevation drawing.
- What coverage should I enter?
- Use usable coverage from the product carton or manufacturer sheet, not the carton’s shipping dimensions or a generic siding square.