Siding Calculator
Estimate siding squares, boxes, waste, and early material cost for exterior walls and gables.
This page starts with siding coverage first. Estimate trim, soffit, fascia, labor, and accessory channels separately after the main siding order is locked.
Last updated: March 28, 2026
Enter Your Siding Project
Fastest for full exterior walls with one average wall height.
Add up all window areas first, then enter one total deduction here.
Do the same for doors so the calculator subtracts one combined opening total.
Add local price (optional)
Get the siding order right first. Add price per box after the quantity makes sense for your product.
Siding Order Summary
Estimate Separately Next
Lock the siding order first, then estimate trim, soffit, fascia, starter strips, accessory channels, and labor separately. Those items do not scale the same way as field siding coverage.
How to Turn Wall Size Into a Siding Order
1. Measure gross wall coverage with perimeter mode or wall sections.
2. Add any gable triangles that also need siding.
3. Subtract windows and doors to get net siding area.
4. Add waste, convert to squares, then convert to boxes or cartons using your product coverage.
Project Examples
Single-Story Ranch
160 ft perimeter · 9 ft wall height · 162 sq ft deductions
At 200 sq ft per box, this layout rounds up to 8 boxes.
A simple ranch is usually easiest to estimate with perimeter × average height, then one waste factor to turn net wall area into siding squares and boxes.
Garage Wall with Gable
24 ft wall · 9 ft height · 1 gable triangle
At 200 sq ft per box, this elevation rounds up to 2 boxes.
A front garage elevation shows why siding calculators need gable math. The rectangular wall may look simple until the gable triangle adds real order area.
Small Shed
48 ft perimeter · 8 ft walls · 2 small gables
At 100 sq ft per box, this shed order rounds up to 5 boxes.
Shed projects are small, but coverage per box matters more because one extra carton can change the order cost quickly.
Siding Planning Decisions
Use perimeter mode for simple exteriors
If the house has one main wall height and you only need an early siding order, perimeter mode is usually the fastest input path.
Use wall sections when one side is different
If one wall run or elevation is being re-sided separately, wall sections make it easier to estimate only the area you actually plan to cover.
Think in squares first, then boxes
Squares are the simplest planning unit for siding area. Boxes or cartons depend on the product coverage listed by the manufacturer.
Raise waste on more cut-up elevations
Simple walls often work with 10% waste. Add more waste when gables, corners, short runs, and trim transitions create extra cuts.
What This Page Covers vs Next
This page covers
Exterior wall area, gable triangles, opening deductions, waste, siding squares, boxes, and an early material cost.
Estimate trim and soffit separately
Trim boards, soffit panels, fascia, J-channel, and corner accessories belong in a separate takeoff because they do not scale the same way as field siding coverage.
Use actual product coverage
Coverage per box or carton can change a lot between vinyl, fiber cement, and engineered wood products. Always use the packaging or spec sheet for your exact material.
Start with net area, not gross walls
The cleaner your opening deductions are, the cleaner your siding order will be. Gross wall area is only the starting point.