Siding Squares Calculator
Work out net wall area and how many squares of siding to order from the house perimeter, wall height, gables and openings. Built for siding contractors doing takeoffs and for homeowners planning a re-side.
Free, no sign-up. Runs in your browser; nothing you type is stored unless you choose to email yourself the results.
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Three steps, about a minute
Step 1
Enter the House perimeter in feet and the Average wall height where siding will be installed.
Step 2
Add the Gable area (total) for all gable triangles, then the Windows & doors area to subtract.
Step 3
Choose a Waste factor for cuts and trim, then read Net wall area and Squares to order.
How the siding squares calculator works
Net wall area = perimeter x average wall height, plus total gable area, minus windows and doors area, and never below zero. Squares to order = net wall area divided by 100, increased by the waste factor. One square of siding covers 100 sq ft. The starting values describe a 180-foot perimeter with 18-foot average walls, 200 sq ft of gables and 250 sq ft of openings. That is 3,190 sq ft of net wall, and with 10% waste you order about 35.1 squares. Find each gable's area as half the base times the rise. The right waste factor depends on the siding profile, the number of corners and how broken up the walls are. Trim, J-channel, corner posts, soffit and fascia are not counted. For a firm order, measure on site or use a professional measurement report.
| House perimeter | 180 ft |
|---|---|
| Average wall height | 18 ft |
| Gable area (total) | 200 sq ft |
| Windows & doors area | 250 sq ft |
| Waste factor | 10% |
| Net wall area | 3,190 sq ft |
|---|---|
| Squares to order | 35.1 |
One square equals 100 square feet of wall coverage.
Using the numbers like a pro: tips for siding contractors
Round your order up to whole cartons for the product you install. Running short mid-job means a second supply run and a real risk of a color or lot mismatch on the wall.
Raise the waste factor on homes with many dormers, bump-outs or short walls between windows. Simple box-shaped houses need less, so one default for every job either wastes material or runs short.
Quote trim, corners, J-channel and house wrap as separate lines from their own linear-foot takeoffs. Folding them into a per-square price hides real material cost on detailed homes.
Put a calculator like this on your own website
Homeowners thinking about new siding want a rough budget before they invite anyone over. A calculator that asks for basic house dimensions and returns squares gives them a starting point. Offer to email a full estimate in exchange for their name and address, and you are first in line for the site visit. Follow up with a measuring appointment, since a number built from rough dimensions is only a starting point.
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Siding Squares Calculator questions
How many square feet is a square of siding?
One square of siding covers 100 square feet of wall. Contractors use squares to order material and often to price labor. To convert, divide the net wall area by 100. A house with 2,000 square feet of wall to cover needs 20 squares before adding waste for cuts, overlaps and trim.
How do you calculate how much siding you need?
Multiply the length of each wall by its height, add the area of each gable triangle (half the base times the height), and subtract windows and doors. Divide by 100 to get squares, then add a waste allowance for cuts and overlaps. Trim pieces, corners and soffit are measured separately, usually by the linear foot.
How much waste should I add when ordering siding?
Waste depends on the siding type and the shape of the house. A simple rectangle with few openings needs less, while homes with many corners, gables, dormers or windows need more. Ten percent is a common starting rule of thumb. Check the manufacturer's installation guide and your own past jobs, and round up to full cartons.
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