Board Foot Calculator
Calculate lumber volume in board feet (BF) from thickness × width × length. Formula: BF = T × W × L / 12 (T and W in inches, L in feet), from the USDA Forest Products Laboratory's definition of one board foot as 144 cubic inches.
Reviewed & updated for 2026 by Rakesh Choudhary, PhDMethodology & sources · How we calculate
Common lumber board foot reference
| Nominal size | BF per linear ft | 8 ft board | 16 ft board |
|---|---|---|---|
| 1 × 4 | 0.33 BF/ft | 2.67 BF | 5.33 BF |
| 1 × 6 | 0.50 BF/ft | 4.00 BF | 8.00 BF |
| 1 × 8 | 0.67 BF/ft | 5.33 BF | 10.67 BF |
| 1 × 10 | 0.83 BF/ft | 6.67 BF | 13.33 BF |
| 2 × 4 | 0.67 BF/ft | 5.33 BF | 10.67 BF |
| 2 × 6 | 1.00 BF/ft | 8.00 BF | 16.00 BF |
| 2 × 8 | 1.33 BF/ft | 10.67 BF | 21.33 BF |
| 2 × 10 | 1.67 BF/ft | 13.33 BF | 26.67 BF |
Why hardwood is priced in board feet (and softwood usually isn't)
Walk into a Home Depot and you'll see 2x4s priced per piece. Walk into a hardwood dealer and you'll see walnut priced per board foot. This isn't arbitrary — the two markets have different economic structures, and the unit reflects how each one actually trades.
Softwood (pine, spruce, fir) is mass-produced from fast-growing plantation trees in standardized dimensions. Almost every 2x4 is the same — same length, same species, same grade. So lumberyards sell them by the piece. A 2x4x8 is a commodity SKU.
Hardwood is different. A walnut log is sawn into boards of varying widths and lengths depending on the tree's geometry. A "1x8" walnut board might actually be 7.5 inches wide on one end and 9 inches on the other, and 11 feet 4 inches long. Pricing each piece individually would be a nightmare. Board feet measures the actual volume of wood you walk out with, regardless of which random pieces the saw produced.
This is also why hardwood prices vary so widely. Fast-growing softwoods that ship easily sell for far less per board foot than slow-growing hardwoods such as walnut, whose best, most figured boards command premium prices for furniture. Ask your supplier for current prices; this page lists none.
Estimating board feet for a real project
Calculator output is volume needed. Actual lumber required is always more, so woodworkers add a waste allowance for defects, planing and offcuts. The allowance is a convention, not a standard; the table below uses 30% for a dining table:
| Component | Finished size | Net BF | With 30% waste |
|---|---|---|---|
| Tabletop (5 boards) | 1" × 8" × 6' | 20.00 | 26.00 |
| Legs (4) | 3" × 3" × 30" | 7.50 | 9.75 |
| Apron rails (4) | 1" × 5" × 5' | 8.33 | 10.83 |
| Breadboard ends (2) | 1" × 4" × 3' | 2.00 | 2.60 |
| Total | — | 37.83 BF | 49.18 BF |
Multiply the total with waste by your supplier's price per board foot to price the wood; enter the same figures in the calculator to check it. Hardware, finish and your time come on top.
Allow more waste than the table if you're ripping wide stock down to narrower pieces, working with figured grain that has more defects, or buying random-width hardwood where you can't pre-select boards.
FAQs
What is a board foot?
The USDA Forest Products Laboratory's Wood Handbook defines it as the lumber in a board 12 in. long, 12 in. wide and 1 in. thick, or any piece with the same volume: 144 cubic inches. The handbook adds that stock thinner than 1 in. nominal is counted as if it were 1 in.
How do I calculate board feet?
Multiply nominal thickness in inches by nominal width in inches by length in feet, and divide by 12; then multiply by the number of pieces. A 1 by 8 that is 10 feet long works out to 6.67 board feet.
What's the difference between board foot and square foot?
A board foot is a volume, so thickness counts; a square foot is only an area. An 8-foot 2 by 4 holds 5.33 board feet, yet laid flat its face covers 2.67 sq ft at the nominal 4-inch width, or 2.33 sq ft at its dressed 3-1/2 inches.
Why is lumber sold in board feet?
Hardwood arrives in random widths and lengths, and a volume unit lets a yard price any mix of pieces fairly. Softwood framing lumber is more often sold by the piece or the linear foot. Wholesale lots are counted in thousands of board feet, abbreviated MBF or MBM.
How much does lumber cost per board foot?
No official source publishes lumber prices, and they vary by species, grade, thickness and region, so this page lists none. Ask your supplier for the price per board foot of the species and grade you want and type it into the calculator to total the order.
What's the difference between nominal and actual lumber sizes?
Nominal is the name you order by, such as a 2 by 4; actual is what arrives after drying and planing, about 1-1/2 by 3-1/2 inches for a surfaced 2 by 4, per the Wood Handbook. The handbook bases the board-foot tally on nominal thickness and width and on actual length, so a board is billed at its nominal size.