Board Foot Calculator
A free board feet calculator with a waste factor and price per board foot: tally mixed lumber into board feet and total cost, or turn a finished cut list into the rough boards to buy. No sign-up.
ExampleA walnut, white oak and poplar order. Edit it or clear it to start your own.
| Pcs | Species | Thick | Width″ | Length′ | $/BF | BF | $ | Actions |
|---|---|---|---|---|---|---|---|---|
| 12.00 | 150.00 | |||||||
| 11.00 | 79.75 | |||||||
| 8.33 | 35.00 | |||||||
| 19.33 | 81.20 |
How it's measured
One board foot is 12″ × 12″ × 1″, or 144 cubic inches (NIST Handbook 130). So board feet = thickness × width × length, all in inches, ÷ 144. With the length in feet, divide by 12 instead.
BF = T × W × L ÷ 144
Quarters. Hardwood thickness is sold in quarters of an inch: 4/4 is 1″, 5/4 is 1-1/4″, 8/4 is 2″. The calculator uses the nominal quarter thickness, because hardwood is measured before it's surfaced (NHLA rules).
Thin stock. Anything under 1″ thick counts as 1″ in hardwood board measure, so a custom 3/4″ thickness is tallied as 1″.
Rough vs surfaced
Rough lumber comes straight from the sawmill; surfaced (S2S) lumber has been planed on both faces. Planing takes off 3/16″ up to 6/4 and 1/4″ from 7/4 to 16/4, so 4/4 surfaces to 13/16″ and 8/4 to 1-3/4″ (NHLA, USDA Wood Handbook). You still pay for the rough thickness.
Finished → rough works backwards from your plan: each finished part gets the smallest quarter that surfaces to its thickness, plus 1/4″ of width and 1″ of length (USDA Forest Service rough-mill allowances), then the list is grouped by species and quarter with about 20% waste (trade guidance, not a rule). The buy quantity rounds up to whole board feet so you don't come home short.
Metric lists use 1″ = 25.4 mm exactly (NIST Handbook 44): 1 board foot = 0.002359737 m³.
How to calculate board feet, with worked examples
Log board foot calculator: Doyle, Scribner and International
Linear feet to board feet converter
Board foot calculator FAQ
How many board feet are in a 2×4×8?
5-1/3 board feet (5.33). Softwood board measure uses the nominal size (NIST PS 20-25, §2.2), so 2 × 4 × 8 ÷ 12 = 5-1/3 (5.33), though a dry 2×4 is actually 1-1/2″ × 3-1/2″. A 1×6×8 is 4 board feet. Both are derived from §2.2, which has no worked example. More sizes: how to calculate board feet.
How do I enter 8/4 lumber or boards thinner than 1 inch?
Pick the quarter, 4/4 to 16/4, in the row's thickness box; the calculator uses the nominal rough thickness, so 8/4 counts as 2″. For any other thickness pick Custom and type it. Anything under 1″ counts as 1″, as thin stock does in hardwood board measure (NHLA ¶16), so a 3/4″ board is tallied at 1″.
How much extra lumber should I buy?
About 20% over the board feet your parts need, for defects, grain and offcuts, and about 50% when the mill picks random widths and lengths. That's trade guidance from Popular Woodworking, not a rule. So 40 BF of parts means buying about 48 BF (our arithmetic). The Finished → rough mode adds 20% by default.
How do I price lumber per board foot or per linear foot?
Cost is board feet × price per board foot. One linear foot of a board is T × W ÷ 12 board feet (T and W in inches, nominal), so $/linear ft = $/BF × T × W ÷ 12. A 1×6 at $9.25/BF is $4.63 per linear foot. That's derived from the board-foot formula, not quoted from a source.
How do I turn a finished cut list into rough lumber to buy?
Pick the Finished → rough tab and enter each part's finished size. The calculator picks the smallest quarter whose S2S thickness is at least the finished thickness (3/4″ parts come from 4/4). By default it adds 1/4″ width, 1″ length (USDA Forest Service) and 20% waste; you can change them. Buy quantities round up to whole board feet.
Can I print a shopping list for the lumberyard?
Yes. The Print shopping list button prints a tally sheet: the date, a blank for the yard, the total, and a checkbox and an empty Tallied BF column on each line, plus the parts table in Finished → rough mode. Copy share link makes a link to the same list, and your browser saves the list between visits.
Does the board foot calculator work in metric?
Yes, in the lumber list: set Units to mm · metres to enter width and custom thickness in mm, length in metres and price per m³, and the total shows cubic metres too. Quarters stay quarters. An inch is exactly 25.4 mm (NIST Handbook 44), so 1 board foot = 0.002359737216 m³ (derived). Finished → rough works in inches.
Sources
- National Institute of Standards and Technology. Handbook 130, Uniform Laws and Regulations: IV-B Method of Sale of Commodities. 2026. Used: §2.12.1.1 Board Foot: the volume of a board 1 ft long, 1 ft wide and 1 in. thick, or its equivalent (144 in³ of wood); §2.12.1.4 surface measure; §2.12.3.1 S4S stock widths: quantity by linear measure (surfaced width and thickness stated), by count (length, surfaced width and thickness stated) or by surface measure in square feet (thickness stated); §2.12.3.2 nominal sizes allowed when marked “nominal” or “nom” and the actual sizes or Table 2 are prominently displayed; Table 2 minimum surfaced sizes for kiln-dried hardwood lumber.
- National Hardwood Lumber Association. Rules for the Measurement & Inspection of Hardwood & Cypress. Effective January 1, 2023. Used: ¶14 standard thicknesses for surfaced (S2S) lumber; ¶16 board measure: standard thicknesses under 1 in. (thin stock) count as 1 in., measured before surfacing.
- National Institute of Standards and Technology. Voluntary Product Standard PS 20-25, American Softwood Lumber Standard. PS 20-25, January 2025. Used: §2.2 board measure computed from nominal size; Table 3 dry dressed sizes.
- USDA Forest Service, Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material, Chapter 6, Commercial Lumber, Round Timbers, and Ties. General Technical Report FPL-GTR-190, 2010. David E. Kretschmann. Used: Table 6-4, standard thickness values for rough and surfaced (S2S) hardwood lumber; footnote a: above 4 in. rough the finished size is not specified (special contract).
- USDA Forest Service, Northeastern Research Station. Rough Mill Improvement Guide for Managers and Supervisors (GTR-NE-329). June 2005. Philip H. Mitchell, Jan Wiedenbeck, Bobby Ammerman. Used: Trim Allowance: the standard 1 in. over the final finished part length; edge allowance: the traditional 1/4 in. of extra width (a 1-3/4 in. rough part machined to 1-1/2 in.).
- Popular Woodworking. Buying Hardwood Lumber – Two Approaches. June 3, 2008. Robert W. Lang. Used: Trade guidance: about 20% extra (a bookcase of a little less than 40 BF, bought 49); about 50% extra when the mill picks the boards (random widths and lengths): a workbench of about 80 BF. Trade guidance, not a rule.
- National Institute of Standards and Technology. Handbook 44, Appendix C: General Tables of Units of Measurement. 2026. Used: 1 inch = 2.54 centimeters (exactly).