Siding Calculator — Squares & Boxes Needed

How the siding calculator works

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.

Frequently asked questions

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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