Siding Calculator: Square Feet, Siding Squares & Waste
Calculate siding square footage, siding squares, waste and estimated packages to order.
Enter wall dimensions or a known exterior wall area, subtract windows and doors, and add a waste allowance to estimate the siding required for the project.
If your siding is packaged by the carton or box, enter its square-foot coverage to calculate the number of full packages to order. Add the package price to estimate primary siding material cost.
Siding products, exposure, package coverage and installation requirements vary. Confirm final quantities using the manufacturer’s specifications and your project takeoff.
Free Siding Calculator
Siding Calculator
Enter your wall measurements or known square footage to estimate siding squares and material needed.
This calculator estimates primary siding coverage. Corners, starter strips, trim, soffit, fascia, flashing, housewrap, fasteners and other accessories are not included. Product coverage and installation requirements vary by manufacturer.
How Much Siding Do I Need?
Start by calculating the square footage of the exterior walls that will receive siding.
For walls of the same height:
Total Wall Length × Wall Height = Gross Wall Area
For example, 160 linear feet of exterior wall with an average height of 9 feet contains:
160 × 9 = 1,440 square feet
If you've already completed a detailed exterior takeoff, select Enter Total Square Feet and enter the gross wall area directly.
What Is a Square of Siding?
A siding square is a unit used to describe siding coverage.
1 siding square = 100 square feet
A project requiring 1,500 square feet of siding therefore requires 15 siding squares before accounting for how the specific product is packaged.
The calculator reports both square footage and siding squares so contractors can work with either measurement.
Should I Subtract Windows and Doors?
Windows, doors and other large openings can be deducted from the gross wall area to determine net siding coverage.
The calculator makes this deduction optional. On projects with many small openings, contractors may choose how detailed they want the takeoff to be because siding still requires cuts around those openings and not every offcut can be reused.
If you want the deduction included, simply enter the combined square footage of the openings.
How Much Extra Siding Should I Order?
Siding projects normally require material beyond the exact net wall area.
Additional material may be needed for:
- End cuts
- Windows and doors
- Gables and rooflines
- Damaged material
- Unusable offcuts
- Complex wall shapes
- Product selection or matching
- Future repairs
A 10% waste allowance is a useful estimating starting point for many straightforward projects, but it is not appropriate for every building.
Simple walls may require less additional material, while buildings with many openings, gables or complicated cuts can require more. Adjust the waste percentage for the actual project.
How Many Boxes or Cartons of Siding Do I Need?
Siding package coverage varies by product. Rather than assuming that every carton contains the same amount, the calculator allows you to enter the actual square-foot coverage per carton or box.
The calculator then divides the siding area, including waste, by the package coverage and rounds up to the next full package.
Use the coverage printed on the product packaging or listed in the manufacturer's specifications.
Siding Calculator Formula
The calculator uses these basic formulas:
Gross Wall Area:
Total Wall Length × Wall Height
Net Wall Area:
Gross Wall Area − Openings
Area With Waste:
Net Wall Area × (1 + Waste % ÷ 100)
Siding Squares:
Area With Waste ÷ 100
If package coverage is entered:
Packages to Order:
Area With Waste ÷ Coverage per Package
The package quantity is rounded up to the next whole carton or box.
Siding Calculator Example
Suppose a project has:
160 linear feet of exterior wall × 9 feet high
The gross wall area is:
160 × 9 = 1,440 square feet
If the project has 200 square feet of windows and doors:
1,440 − 200 = 1,240 square feet
Adding 10% waste gives:
1,240 × 1.10 = 1,364 square feet
In siding squares:
1,364 ÷ 100 = 13.64 siding squares
If the selected siding comes in cartons covering 200 square feet each:
1,364 ÷ 200 = 6.82 cartons
The estimated order quantity would therefore be:
7 cartons
What Does This Siding Calculator Include?
This calculator estimates the primary siding material covering the wall surface. It does not separately calculate:
- Inside or outside corners
- Starter strips
- J-channel or trim
- Soffit
- Fascia
- Housewrap
- Flashing
- Fasteners
- Mounting blocks
- Other siding accessories
Those quantities depend on the siding system and building details and should be estimated separately.
Use Siding Cost to Build Your Estimate
Siding is only one part of the project cost. Contractors may also need to account for trim, housewrap, flashing, fasteners, equipment, demolition, disposal, delivery, labor and overhead.
Once you know the expected siding cost, use the Contractor Job Cost Calculator to build the rest of the job cost. Then use the Contractor Markup Calculator or Contractor Profit & Margin Calculator to check your selling price and expected profitability.
Frequently Asked Questions
What is a square of siding?
One siding square represents 100 square feet of siding coverage.
How do I calculate how much siding I need?
Calculate the exterior wall area, subtract any openings you want deducted, add an appropriate waste allowance, and divide by 100 to convert the result into siding squares.
Should I subtract windows and doors from siding?
Large windows and doors can be deducted for a more detailed takeoff. The calculator allows you to enter the combined square footage of openings or leave the deduction at zero.
How much extra siding should I order?
Ten percent is a useful starting point for many straightforward siding projects, but the appropriate allowance depends on openings, gables, cuts, wall shapes and the specific siding product.
How many square feet are in a box of siding?
Package coverage varies by siding product and manufacturer. Check the product packaging or specifications and enter the actual square-foot coverage into the calculator.
Does this calculator include trim and accessories?
No. It estimates primary siding coverage. Corners, starter strips, trim, soffit, fascia, flashing, housewrap, fasteners and other accessories should be calculated separately.