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Siding Calculator

This siding calculator finds the square footage and cost of siding for your house.

Leave at zero to use the dimensions above.
Extra to cover offcuts, breakage and mistakes.
Leave at zero to skip the costing.
Clear
Boards needed5953.33 to cover it, plus 10% waste
Exposure per course6.75 in8 in board less 1.25 in overlap
Courses up the wall17over 9 ft of height
Exposure to land evenly6.3529 inadjust slightly so the top course is full width
Effective coverage per board6.75 sq ft8 sq ft of board, 15.6% of it hidden
Net wall area360 sq ft
Linear feet of board708 ft

The method

courses = wall height ÷ exposure; exposure = board width − overlap

Overlap is dead area you still pay for

An 8-inch lap board with a 1¼-inch overlap exposes only 6¾ inches, so about 16% of every board you buy is hidden behind the course above. That is why lap siding always needs more material than the wall area suggests.

Set the exposure so the courses land evenly — a full course at the top looks right and a two-inch sliver does not. Divide the wall height by the number of courses and adjust the exposure slightly rather than cutting the last board down.