Lumber Board-Foot Calculator
Board foot calculator — enter a board’s nominal thickness in inches, width in inches and length in feet, plus how many you need, to get the total board feet. The standard unit hardwood lumber is priced and sold by. Runs in your browser.
Lumber Board-Foot Calculator
How to Use the Board Foot Calculator
Enter thickness & width
In inches — use nominal size for pricing.
Enter length
In feet.
Set quantity
How many identical boards.
Read board feet
Use the total to price; add 15–20% for defects.
The Unit Hardwood Is Sold In
If you have ever stood at a hardwood lumber yard wondering why the price is quoted “per board foot” rather than per plank, this is the calculator that makes sense of it. A board foot is a measure of volume — 144 cubic inches, the amount of wood in a board one inch thick, twelve inches wide and one foot long. Because hardwood boards come in random widths and lengths rather than tidy standard sizes, pricing by volume is the only fair way to compare them: a wide board and a narrow board of the same thickness and length are charged in proportion to how much timber each actually contains.
The formula is simple — thickness in inches times width in inches times length in feet, divided by twelve — and this tool applies it across however many identical pieces you enter. A 2-by-6 at eight feet is eight board feet; five of them are forty. The one subtlety worth getting right is nominal versus actual dimensions. For pricing, use the nominal (rough-sawn) size, because that is how the yard calculates the charge, even on surfaced boards. For fitting pieces into a project, use the smaller finished size. Hardwood thickness is also quoted in the quarter system — 4/4 is one inch rough, 8/4 is two inches — which maps directly onto the inches you type here.
Knowing the board-foot total tells you what the wood will cost, but not how much to buy, and the gap between the two is bigger for lumber than almost any other material. Real boards carry knots, splits, end checks and wane that you cut around, and joinery itself generates offcuts, so the usable yield from a stack of rough lumber is well below its board-foot figure. Woodworkers routinely add fifteen to twenty percent over the finished requirement, more for highly figured or defect-prone stock. It is also worth distinguishing the board foot from the linear foot: the latter measures length alone and is common for standard-dimension softwood and trim, and the two are not interchangeable, so always confirm which a supplier is quoting. Use the board-foot total here to price and order with confidence, pad it for yield, and your project will not stall for want of timber. As always, the calculation runs entirely in your browser.
Board feet tell you the price; yield tells you the quantity — rough hardwood always gives less usable wood than its board-foot figure suggests.
10 Facts About Board Feet
A board foot is 144 cubic inches of wood.
Formula: thickness × width × length(ft) ÷ 12.
Hardwood is priced per board foot, not per plank.
A 1″×12″×1′ board is exactly one board foot.
Use nominal (rough-sawn) dimensions to price.
Quarter system: 4/4 = 1″, 8/4 = 2″ thick.
Planed (S4S) boards are thinner than nominal.
Always buy 15–20% extra for defects and cuts.
Softwood is often sold by the linear foot instead.
This calculator runs in your browser — nothing is uploaded.
Frequently Asked Questions
- A board foot is a unit of lumber volume equal to 144 cubic inches — the amount of wood in a board one inch thick, twelve inches wide and one foot long. It is the standard way hardwood lumber is measured, priced and sold in North America, because it fairly compares boards of different dimensions by their actual volume of wood.
- Multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. For example, a board 2 inches thick, 6 inches wide and 8 feet long is (2 × 6 × 8) ÷ 12 = 8 board feet. Multiply by the number of identical pieces for the total, which is exactly what this calculator does.
- For pricing, use the nominal (rough-sawn) dimensions, because that is how lumber yards calculate board feet and charge you — even surfaced boards are usually priced on their pre-planing size. For fitting pieces into a project, use the actual finished dimensions, which are smaller. The two purposes need different numbers.
- Hardwood thickness is quoted in quarters of an inch. 4/4 (“four-quarter”) means one inch thick in the rough, 5/4 means 1.25 inches, 8/4 means two inches, and so on. When you enter thickness in inches here, 4/4 is 1, 8/4 is 2. The quarter system refers to the rough thickness before surfacing.
- Because hardwood boards come in random widths and lengths rather than standard dimensions, pricing per plank would be unfair. The board foot measures the actual volume of usable wood, so a wide board and a narrow board of the same length and thickness are priced in proportion to how much timber they contain. Softwood, sold in standard sizes, is often priced per linear foot instead.
- Allow 15 to 20 percent over the finished requirement for hardwood. Real boards have knots, splits, checks and wane that you cut around, and joinery generates offcuts. Rough lumber especially yields less usable material than its board-foot figure suggests once defects are removed, so a generous allowance is normal in woodworking.
- The board foot is an imperial unit, so this calculator takes thickness and width in inches and length in feet. If your timber is metric, convert first (1 inch = 25.4 mm, 1 foot = 0.3048 m). Much of the world prices softwood by the cubic metre or linear metre instead, in which case board feet may not apply.
- A linear foot measures only length, ignoring width and thickness, and is common for standard-dimension softwood and trim. A board foot measures volume, accounting for all three dimensions, and is used for random-width hardwood. Make sure you know which unit a supplier is quoting, because they are not interchangeable.
- The board-foot maths is exact for the dimensions you enter. What varies in practice is yield — how much of that lumber survives once you cut around defects and trim to size — which is why the waste allowance matters. Use the board-foot total to price and order, and add 15 to 20 percent for a real project.
- Completely free, with no account or limit. It works offline once the page has loaded and collects no data.
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