Board Foot Calculator
Board feet = thickness × width × length (all inches) ÷ 144. Thickness pills are lumber-yard quarters: 4/4 = 1", 5/4 = 1¼", 6/4 = 1½", 8/4 = 2". Rough lumber is charged at nominal thickness — pick the quarter you're buying, not the planed size.
How to use this calculator
Add a row for each board, tap the thickness you're buying, enter width in inches and length in feet or inches, set the quantity — and give each board its own price per board foot, because your walnut and your poplar don't cost the same. Every board shows its own board feet and its own cost, with project totals running at the bottom. Prices are optional; skip them and you still get board feet. "Copy cutlist" gives you a plain-text list you can paste into a note or text straight to the yard.
A board foot is a volume measure — one board foot is a piece 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). Hardwood is priced this way because boards come in random widths and lengths; the yard charges for wood volume, not per stick. Two things trip people up: rough lumber is measured at its nominal rough thickness (a planed "1 inch" board usually started as 4/4 and you pay for the 4/4), and length is often rounded down to the nearest foot at the yard. When in doubt, this calculator plus a 10–15% waste allowance is the honest way to order.
Buying for outdoor projects? Species matters as much as quantity — our guide to the best wood for outdoor signs covers which boards survive weather, and the outdoor finish guide covers what to put on them.
Put this calculator on your own site
Woodworking club page, guild site, or shop blog? You're welcome to embed this calculator free — copy the code below. It shows the live calculator and credits this page as the source.
Frequently Asked Questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in inches, then divide by 144. A board 1" thick, 6" wide, and 8 feet (96") long is 1 × 6 × 96 ÷ 144 = 4 board feet. For rough hardwood, use the nominal quarter thickness you're buying — 4/4, 5/4, 6/4, or 8/4.
What does 4/4, 5/4, or 8/4 lumber mean?
Quarters describe rough thickness in quarter inches: 4/4 ("four-quarter") is 1 inch, 5/4 is 1¼", 6/4 is 1½", and 8/4 is 2 inches. After drying and planing, a 4/4 board typically finishes around 13/16", but you're charged for the rough 4/4 measurement.
How many board feet should I buy for a project?
Total your cutlist with the calculator, then add 10–15% for waste from defects, grain matching, and mistakes — more like 20–30% if the project needs matched grain or the species has lots of knots. It's cheaper to buy the margin up front than to make a second trip for one board from a different batch.