How this calculator works
It multiplies your total wall length by the average height for the gross area, subtracts 21 sq ft per door and 15 sq ft per window, then converts to siding “squares” (each covering 100 sq ft) and adds 10% for cuts and waste.
Worked example — a house with 120 ft of wall at 9 ft height, 3 doors and 8 windows:
120 × 9 = 1,080 sq ft − (63 + 120) = 897 sq ft net → ÷ 100 × 1.10 = 9.9 squares → buy 10.
120 × 9 = 1,080 sq ft − (63 + 120) = 897 sq ft net → ÷ 100 × 1.10 = 9.9 squares → buy 10.
How siding is sold
Vinyl siding is sold by the “square” — a unit covering 100 sq ft. Each carton typically includes several panels and covers one square. Always check the carton label, as coverage can vary by panel style.
Frequently asked questions
How many squares of siding do I need?
Measure total wall area, subtract openings, divide by 100, and add 10% for waste. A typical 1,500 sq ft ranch-style house takes roughly 12–15 squares.
How much does vinyl siding cost per square?
Material cost runs roughly $80–$150 per square; installed cost is typically $100–$200 per square.