How it works
Enter the house outline and wall height and the calculator finds the wall area, adds triangular gable ends, subtracts doors and windows and converts to squares, the unit siding is sold in.
Gable area is half the house width times the gable height, assumed to sit over the shorter walls. Measure gable height from the top of the wall to the peak. For complex houses, measure each wall separately and add them up.
Ten percent waste is typical for simple rectangular houses; use 15% for houses with many corners, dormers or gables. Vinyl siding usually comes 2 squares to a box.
Formula
Net area = 2 × (L + W) × H + gables × ½ × W × gable height − 20 sq ft per door − 15 sq ft per window. Squares = net area × (1 + waste) ÷ 100.
Questions people ask
How much area is a square of siding?
100 square feet of wall coverage, the same unit used for roofing.
How many boxes of vinyl siding per square?
Most vinyl siding boxes contain 2 squares (200 sq ft), so one box covers two squares.
Should I subtract windows and doors?
Yes for large openings like garage doors and picture windows. Many installers ignore small windows because the cut pieces seldom fit elsewhere; the waste factor covers that.