Siding Calculator
Calculate siding squares, trim and corner posts for an exterior wall.
About Siding Calculator
Siding is sold by the square regardless of the metric area measured, so the conversion is the first step. Corner posts and trim are linear items priced separately from the field material. Trim and corner posts often approach a third of siding cost, so estimating only the field area understates the job substantially.
Formula
Siding
One siding square covers 100 square feet, or 9.29 m²
- square
- The trade unit for siding, equal to 100 square feet
- starter strip
- Runs the full perimeter at the base of the wall
Worked example
With the default values below, Siding Calculator returns Siding Squares Required of 18.47. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Total wall areaminimum 0 m2
- 180 m2
- Windows and doors to deductminimum 0 m2
- 24 m2
- Outside cornersminimum 0
- 4
- Wall heightminimum 0.1 m
- 2.7 m
- Waste allowanceaccepts 0–50 %
- 10 %
Results
- Siding Squares Required
- 18.47
- Net Area to Cover
- 156.00 m2
- Corner Post Length
- 10.80 m
- Starter Strip Length
- 57.78 m
- Trim Around Openings
- 23.52 m
Step by step
- 1Values used
- 2Siding
- 3Siding Squares Required= 18.47
- 4Net Area to Cover= 156.00 m2
- 5Corner Post Length= 10.80 m
- 6Starter Strip Length= 57.78 m
- 7Trim Around Openings= 23.52 m
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Siding calculated?
One siding square covers 100 square feet, or 9.29 m² Siding is sold by the square regardless of the metric area measured, so the conversion is the first step. Corner posts and trim are linear items priced separately from the field material.
Why does Siding matter?
Trim and corner posts often approach a third of siding cost, so estimating only the field area understates the job substantially.
What values do I need to enter?
This calculator takes 5 inputs: Total wall area, Windows and doors to deduct, Outside corners, Wall height, Waste allowance. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.