Board Foot Calculator (Lumber Tally and Cost)
Board measure is thickness in inches times width in inches times length in feet, divided by 12 — and every one of those numbers is the nominal size on the tag, not what a tape reads on the board. Enter a size, a length and a count and this calculator returns board feet per piece, the total tally, MBF and your cost.
Board feet
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Results are estimates for planning purposes. Verify with your supplier, engineer, or a qualified professional before ordering material or performing work.
Nominal size, dressed size, and which one you pay for
You tally and pay for the number on the tag. You build with what comes off the truck. These are the minimum dressed sizes for dry lumber in the American Softwood Lumber Standard — the widths apply to all thicknesses and the thicknesses to all widths.
| Nominal | Dressed dry | BF per lineal ft | BF in an 8 ft piece |
|---|---|---|---|
| 1 × 4 | 3/4 × 3 1/2 in | 0.333 | 2.67 |
| 1 × 6 | 3/4 × 5 1/2 in | 0.500 | 4.00 |
| 5/4 × 6 | 1 × 5 1/2 in | 0.625 | 5.00 |
| 2 × 4 | 1 1/2 × 3 1/2 in | 0.667 | 5.33 |
| 2 × 6 | 1 1/2 × 5 1/2 in | 1.000 | 8.00 |
| 2 × 8 | 1 1/2 × 7 1/4 in | 1.333 | 10.67 |
| 2 × 10 | 1 1/2 × 9 1/4 in | 1.667 | 13.33 |
| 2 × 12 | 1 1/2 × 11 1/4 in | 2.000 | 16.00 |
| 4 × 4 | 3 1/2 × 3 1/2 in | 1.333 | 10.67 |
| 6 × 6 | 5 1/2 × 5 1/2 in | 3.000 | 24.00 |
Dressed sizes: NIST PS 20-20 Table 3, minimum dressed dry (19% maximum moisture content). Green lumber of the same nominal size is dressed slightly fuller — a green 2x6 is 1 9/16 by 5 5/8 in. Timbers 5 in and thicker are dressed 1/2 in off the nominal size. Board feet per lineal foot are figured on the nominal size, which is why a 2x6 comes out at exactly 1.0.
Before you price the take-off
- A board foot is a tally unit, not a volume. PS 20-20 Appendix B quotes IEEE/ASTM SI 10 word for word: no conversion is given for board foot, because board foot is not a well-defined unit of volume. That is also why there is no metric toggle on this page.
- Overlength is normal. PS 20 allows lumber 2 in or less in nominal thickness to run up to 3 in over its nominal length. You tally the nominal length, not what the tape says.
- Board measure says nothing about strength. Species, grade and span come from your drawings or from the American Wood Council publications, never from a quantity calculator.
- Check the basis before you compare two quotes. $0.85/BF and $850/MBF are the same price. $4.20 per 8 ft 2x4 is $0.79/BF. Yard pricing per piece and mill pricing per MBF are not comparable until you convert.
- Add your own waste. This tool tallies exactly what you entered. Cutting waste, culls and defect allowance are yours to add, and they depend on the grade you bought and the cut list you are working from.
How it's calculated
- Board measure (one piece)
BF = nominal thickness (in) × nominal width (in) × length (ft) / 12PS 20-20 section 2.2 states board measure as nominal thickness in inches × nominal width in FEET × length in feet. Dividing the width in inches by 12 is the same arithmetic and is how the trade writes it. Every dimension in this formula is the nominal size, never the dressed size.- Total tally
total BF = BF per piece × number of pieces- Thousand board feet
MBF = total BF / 1,000MBF is how mills, wholesalers and estimators quote volume. MBM and FBM in the same documents mean thousand feet board measure and foot board measure.- Lineal feet
lineal ft = length per piece (ft) × number of piecesLineal footage is what you need for trim, blocking and anything priced by the running foot. It is not interchangeable with board feet: 100 lineal ft of 2x4 is 66.7 BF, 100 lineal ft of 2x12 is 200 BF.- Cost
cost = total BF × $/BF, or MBF × $/MBF, or pieces × $/each
Frequently asked questions
Multiply nominal thickness in inches by nominal width in inches by length in feet, then divide by 12. A 2x6 that is 12 ft long is 2 × 6 × 12 / 12 = 12 board feet. Ten of them make a 120 BF tally.
The nominal size. NIST PS 20-20 section 2.2 defines board measure on nominal thickness and width, and Appendix B of the same standard warns that a board foot is not a well-defined unit of volume because of it. A 2x4 measures 1 1/2 by 3 1/2 in dry, but you still tally and pay for it as 2 by 4.
Two thirds of a board foot per lineal foot: 2 × 4 / 12 = 0.667 BF/ft. An 8 ft 2x4 is 5.33 BF, a 92 5/8 in precut stud is 5.15 BF.
Thousand board feet — the unit mills and wholesalers quote in. Divide your board foot total by 1,000. A 12,000 BF order is 12 MBF; at $650/MBF that is $7,800.
Divide the board feet by the board feet per lineal foot of that size, which is nominal thickness times nominal width divided by 12. For a 2x6 that factor is 1.0, so 120 BF is 120 lineal ft. For a 2x4 the factor is 0.667, so 120 BF is 180 lineal ft.
Yes. 5/4 is a nominal 1 1/4 in thickness, so a 5/4 x 6 board 16 ft long is 1.25 × 6 × 16 / 12 = 10 BF. PS 20 Table 3 lists its dry dressed size as 1 in thick by 5 1/2 in wide.
Because there is no honest one. PS 20-20 Appendix B quotes IEEE/ASTM SI 10 directly: no conversion is given for board foot, because board foot is not a well-defined unit of volume. It is a nominal tally unit, not a measurement of the wood you receive.
Sources & references
- NIST Voluntary Product Standard PS 20-20 (Revision 1, October 2021), American Softwood Lumber Standard — section 2.2 board measure, section 2.16 nominal size, Table 3 nominal and minimum-dressed sizes of boards, dimension and timbers, and Appendix B on board foot conversions — Published by NIST with the American Lumber Standard Committee. This is the standard that defines what a nominal 2x4 is in the United States.
- American Wood Council — wood product standards and design publications — Where span tables, design values and the Wood Frame Construction Manual live. Board measure does not tell you whether a member is strong enough.
Content checked against these sources — last reviewed September 19, 2026.