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Siding Calculator
Estimate siding squares and boxes for any exterior wall.
Siding is quoted in squares (100 sq ft): multiply each wall's length × height, add gable triangles (½ × base × height), subtract windows and doors, divide by 100, then add 10% waste — 15% for lap siding on complex walls. Enter your wall dimensions to get squares, boxes of vinyl or lap-siding courses plus trim.
How does the siding calculator work?
Siding area = gross wall area − doors and windows. Add 10% for cut waste. A "square" is 100 ft². Boxes typically cover 200 ft² for vinyl and less for fiber cement.
What else do people ask about this calculator?
How many boxes of vinyl siding do I need?
One box = 2 squares (200 ft²). A 1,200 ft² wall (net) needs 6 boxes plus 10% waste = 7 boxes.
How much extra siding should I order?
10% for straight gable walls; 15% for cut-up walls with dormers or many openings.
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