Clapboard and Lap Siding Calculator
Find how many linear feet and 12 ft boards of cedar or fiber cement lap siding a wall needs, by exposure.
Change the values and press Calculate to work out your own figures.
Enter the wall's size and choose the siding.
Show the working
- linear feet = (wall area − openings) ÷ exposure
- boards = linear feet ÷ 12
How to use it
Enter the wall's size and choose the siding.
Lengths can be decimals, fractions or tape entries such as 12' 6 1/2" (in feet or inches). Prices are optional.
Key facts
linear feet = (wall area − openings) ÷ exposure; boards = linear feet ÷ 12
Exposure
The exposure is the part of each board left showing: its width less the overlap (at least 1–1 1/2 in).
Questions
How much 6 in cedar siding for a 20 × 12 ft wall?
720 linear ft (60 boards of 12 ft) at a 4 in exposure.
Formulas
linear feet = (wall area − openings) ÷ exposure; boards = linear feet ÷ 12
Sources
Limitations
- Material densities are typical values (the midpoint of the commonly published range); real loads vary with moisture, grading and compaction, so check with your supplier or type in their density.
- Tank results are the geometric volume; real tanks have wall thickness and fittings.