Board Foot Calculator
A board foot is 144 cubic inches — 1 inch thick by 12 inches wide by 12 inches long. The formula is (nominal thickness × nominal width × length in feet) ÷ 12. Twenty-four 12 ft 2×6s come to 288 board feet. Critically, board feet use NOMINAL sizes: a 2×4 is really 1.5" × 3.5" but bills as 2" × 4". Dimension standards verified 2026-08-04.
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Board Foot Calculator — materials list
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Prepared with MaterialMath — https://estimatormath.com. Quantities are estimates based on the dimensions entered and the published figures cited on the tool page (verified 2026-08-04). Verify against your own measurements and your supplier's actual pack sizes before ordering. Not professional engineering, construction or financial advice.
How are board feet calculated?
A board foot is a unit of volume: 144 cubic inches, which is one inch thick by twelve inches wide by twelve inches long. Because it is a volume rather than a length, it lets you price a 2×4 and a 1×12 on the same basis, which is the whole point of it.
Nominal, not actual — the 34% error
The dimensions in that formula are the nominal ones. A 2×4 has not measured two inches by four inches since lumber started being surfaced; it measures 1.5" × 3.5". But the industry bills it as 2" × 4", and every price per board foot you will be quoted assumes that.
Use the actual dimensions and an 8 ft 2×4 comes out at 2.80 board feet instead of 5.33. That is a 47% undercount on that piece, and it will make every price comparison you do wrong in the same direction. This calculator uses nominal for the board-foot figure and actual only for the weight estimate, because weight is about the wood that physically exists rather than the wood you are billed for.
A worked example: framing lumber for a small deck
Twenty-four 12 ft 2×6 joists, six 16 ft 2×8 beams, six 8 ft 4×4 posts. Southern yellow pine at $1.45 per board foot, 15% waste.
Line by line
- 24 × 2 × 6 at 12 ft
- (2 × 6 × 12) ÷ 12 × 24 = 288.0 bf (288 linear ft)
- 6 × 2 × 8 at 16 ft
- (2 × 8 × 16) ÷ 12 × 6 = 128.0 bf (96 linear ft)
- 6 × 4 × 4 at 8 ft
- (4 × 4 × 8) ÷ 12 × 6 = 64.0 bf (48 linear ft)
- Net total
- 480.0 board feet across 36 pieces
- With 15% waste
- 552.0 board feet
- Total linear feet
- 432 ft
- Estimated weight (SYP)
- about 1025 lb
The weight line is worth a look before you plan the delivery. That is 0.5 tons of lumber, computed from the actual dressed volume rather than the nominal one. If it arrives green and pressure-treated it will be heavier still — freshly treated stock can run 50% above the kiln-dried figure until it dries out.
Who this calculator is for
- Woodworkers buying hardwood, which is priced by the board foot and nothing else. Tick the hardwood box for the tally warnings.
- Builders comparing quotes where one supplier prices by the piece and another by the board foot.
- Anyone estimating a framing order from a cut list — six lines covers most small projects, and the linear-foot column tells you what to actually ask for at the counter.
- People planning delivery or transport, where the weight estimate matters more than the volume.
Framing a deck? The deck calculator produces the piece counts and this one converts them to board feet for pricing. For fence rails and pickets, the fence calculator does the same job.
What this calculator does not account for
- Grade. Select, #1, #2 and utility grades of the same size differ substantially in price and in how much you can use. Board feet are blind to grade.
- Random tally. Hardwood is sold in the widths and lengths that come off the pile. Your cut list determines what you can use, not what you can buy.
- Milling loss. Rough-sawn 4/4 planes down to about 13/16", and jointing an edge costs width. If you are milling your own, buy thicker and wider than the finished dimension.
- Moisture content. The weight figures assume 12%. Green lumber is much heavier, and it will also shrink as it dries — across the width, mostly, which is where cupping comes from.
- Treatment. Pressure-treated lumber is heavier when fresh and is priced differently. Ground-contact and above-ground ratings are different products.
Nominal versus actual, and board feet per linear foot
| Nominal | Actual | Board ft per linear ft | Board ft in an 8 ft piece |
|---|---|---|---|
| 1 × 4 | 0.75″ × 3.5″ | 0.333 | 2.67 |
| 1 × 6 | 0.75″ × 5.5″ | 0.500 | 4.00 |
| 1 × 12 | 0.75″ × 11.25″ | 1.000 | 8.00 |
| 5/4 × 6 | 1″ × 5.5″ | 0.625 | 5.00 |
| 2 × 4 | 1.5″ × 3.5″ | 0.667 | 5.33 |
| 2 × 6 | 1.5″ × 5.5″ | 1.000 | 8.00 |
| 2 × 8 | 1.5″ × 7.25″ | 1.333 | 10.67 |
| 2 × 10 | 1.5″ × 9.25″ | 1.667 | 13.33 |
| 2 × 12 | 1.5″ × 11.25″ | 2.000 | 16.00 |
| 4 × 4 | 3.5″ × 3.5″ | 1.333 | 10.67 |
| 6 × 6 | 5.5″ × 5.5″ | 3.000 | 24.00 |
Actual dimensions per US Voluntary Product Standard PS 20. Note that boards 8 inches and wider lose 3/4" to surfacing rather than 1/2" — a 1×8 is 7.25" wide, not 7.5".
Common questions
What is a board foot?
A board foot is 144 cubic inches of lumber — a piece 1 inch thick, 12 inches wide and 12 inches long. It is a volume measure, which is why it lets you compare a 2×4 against a 1×12 on the same basis.
The formula is (thickness in inches × width in inches × length in feet) ÷ 12. So an 8 ft 2×4 is (2 × 4 × 8) ÷ 12 = 5.33 board feet.
Do I use nominal or actual dimensions for board feet?
Nominal. Always. This is the single most common board-foot error and it is a large one.
A 2×4 measures 1.5" × 3.5" in real life, but the industry bills it as 2" × 4". Using the actual dimensions gives 2.8 board feet for an 8 ft piece instead of 5.33 — you would under-count by 34%. The nominal size is a billing convention that dates from before lumber was surfaced, and it has stuck.
How is hardwood board footage different?
Hardwood is measured in quarters of an inch of rough thickness — 4/4 is one inch, 8/4 is two — and on the actual measured width rather than a nominal one. A 4/4 board surfaced down to 13/16" is still sold and billed as 4/4.
The bigger practical difference is that hardwood comes as a random-width, random-length tally. You cannot order "20 board feet of 6-inch walnut" and receive exactly that. Expect to buy 15–20% over your cut list and do your own ripping, and expect a higher waste factor than softwood because you are culling around knots, checks and sapwood.
How do I convert board feet to linear feet?
You need the size. Linear feet is just length; board feet is volume. For a given nominal size, board feet per linear foot = (thickness × width) ÷ 12.
A 2×4 is (2 × 4) ÷ 12 = 0.667 board feet per linear foot, so 100 board feet of 2×4 is 150 linear feet. A 2×12 is 2 board feet per linear foot, so the same 100 board feet is only 50 linear feet. This tool reports both for every line.
How much does lumber weigh?
It depends on species and moisture content, and the spread is wide. At about 12% moisture — the equilibrium for most interior US environments — spruce-pine-fir runs about 28 lb per cubic foot, southern yellow pine about 37, and white oak about 48.
This tool estimates weight from the actual dressed volume rather than the nominal, because the weight you have to lift is the wood that physically exists. Green pressure-treated lumber is substantially heavier than the kiln-dried figures — often 50% more when freshly treated.
How much waste should I allow on a lumber order?
15% is a reasonable default for softwood framing from a cut list, and it is what this tool starts with. It covers trim cuts, the pieces you cut a quarter inch short, and boards culled for crook or wane.
Hardwood needs 25–30%, because you are cutting around defects and working from random widths. If you are buying rough-sawn and milling it yourself, add more still — you lose thickness to planing on both faces.
Sources for the figures used
Every rate, coverage figure and code limit in this calculator comes from a published source. Where a figure is a convention rather than a standard, it says so.
- US Voluntary Product Standard PS 20 — American Softwood Lumber Standard — Nominal-to-actual dressed dimensions for all softwood sizes (checked 2026-08-04)
- Western Wood Products Association — Grading rules and dimension standards (checked 2026-08-04)
- National Hardwood Lumber Association grading rules — Quarter thickness conventions and random-width tally practice (checked 2026-08-04)
- USDA Forest Products Laboratory Wood Handbook — Species densities at 12% moisture content (checked 2026-08-04)