Board Foot Calculator
Board feet from the thickness, width and length of each piece, for up to four lumber sizes, with the linear feet and, at your own price, the cost.
The working
Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12 × Pieces
= 1 × 6 × 8 ÷ 12 × 1
= 4 bd ft
Linear feet = Length × Pieces
= 8 × 1
= 8 ft
Volume = Board feet ÷ 12
= 4 ÷ 12
= 0.333 cu ft
Board feet
bd ft
From the sizes entered; board measure uses nominal sizes (PS 20-25 §2.2). Exact: no tally rounding.
- Board feet per piece
- 4bd ft
- Linear feet
- 8ft
- Pieces
- 1pieces
- Volume at the sizes entered
- 0.333cu ft
A board foot is 144 cubic inches: a board 1 inch thick, 12 inches wide and 1 foot long. Enter each size the way your seller tallies it, nominal for softwood (a 2x4 is 2 by 4) and rough thickness in quarters for hardwood (8/4 is 2 inches), with the number of pieces. The calculator adds up the board feet, the linear feet and the volume at those sizes, and prices the total only at a price you enter. It rounds nothing, so a seller’s tally can come out a little different; the method below says why.
How this calculator works
Only your inputs and exact unit conversions. Where a figure comes from anywhere else, it is recorded below with its source.
- Formula version
- 1.0.0
- Last reviewed
- 2026-09-29
- External data
- 4 sources
- Category
- Measurement
What this calculates
The board feet in one or more sizes of lumber, the linear feet, the number of pieces, and the volume at the sizes you entered. With a price per board foot or per thousand board feet it also gives the cost. Up to four sizes can be entered at once; each size is a thickness, a width, a length and a number of identical pieces.
The formula
Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12 for one piece, times the number of pieces. With every dimension in inches the same thing is Thickness × Width × Length ÷ 144.
Both forms come from the definition. NIST Handbook 130-2026 defines a board foot as “the volume of a board 1 ft long, 1 ft wide, and 1 in thick or its equivalent (144 in³ of wood)” (§2.12.1.1). The American Softwood Lumber Standard, PS 20-25, obtains the board feet in a piece “by multiplying the nominal thickness in inches or fraction of an inch by the nominal width in feet by the length in feet” (§2.2). A width in inches divided by 12 is the width in feet, which gives the formula above.
Thickness in quarters: the American Hardwood Export Council (AHEC) writes that “standard thickness for rough sawn lumber is expressed in quarters of an inch”, so 4/4 is 1 inch, 5/4 is 1 1/4, 6/4 is 1 1/2 and 8/4 is 2 inches. The calculator divides the quarters by 4 to get inches.
Metric entries are converted exactly: 1 inch is 25.4 mm and 1 foot is 0.3048 m. So 25.4 mm × 152.4 mm × 2.4384 m is 1 in × 6 in × 8 ft, and 1 × 6 × 8 ÷ 12 = 4 board feet.
Linear feet = Length × Pieces. Volume at the sizes entered = Board feet ÷ 12 cubic feet, because a cubic foot is 1,728 cubic inches and a board foot 144.
Cost = Board feet × your price. A price per MBF is a price per thousand board feet (PS 20-25, Appendix C: “M” is thousand; the Wood Handbook lists MBF as thousand board measure), so it is divided by 1,000 first. An overage you enter is added to the board feet before they are priced.
Nominal or actual size
Board feet are counted on nominal sizes, not on the dressed size of the finished board. PS 20-25 §2.2 multiplies the nominal thickness by the nominal width, and §2.16 defines a nominal size as the label designation for a size category, greater than the dressed size: “a dry 2 by 4 is surfaced to 38.1 mm by 88.9 mm (1 1/2 by 3 1/2 inches)”. NIST Handbook 130-2026 §2.10 says the same of a dry 2 × 4.
So an 8 ft 2x4 is 2 × 4 × 8 ÷ 12 = 5.333 board feet, although its dressed cross-section is 1 1/2 by 3 1/2 inches. Entered at the dressed size, the same piece would give 1.5 × 3.5 × 8 ÷ 12 = 3.5 board feet, which is not how PS 20-25 counts it. Lumber finished to a nonstandard size is tallied at the rough or nominal size it was made from (§4.2).
The Wood Handbook (USDA Forest Products Laboratory, 2021, chapter 6) notes that lumber length is recorded in actual dimensions while width and thickness are traditionally recorded in nominal dimensions (p. 6-10), and that a board measure depends on which dimensions are used, so buyer and seller should be clear about them (p. 6-17).
Hardwood is described by its rough-sawn thickness in quarters. Surfaced on two sides, 4/4 is 13/16 inch in the Wood Handbook’s Table 6-4; AHEC takes 3/16 inch off the nominal thickness for lumber 1 1/2 inches and under, and 1/4 inch for 1 3/4 inches and over. Ask whether your seller tallies surfaced hardwood at its rough or its surfaced thickness, and enter that.
Why a seller’s tally can differ
This calculator rounds nothing. Trade tallies can round in several places:
- Hardwood length at retail: NIST Handbook 130-2026 lists standard lengths of 4 to 16 ft in whole feet and rounds a fractional length down to the next lower standard length, so a board 6 ft 8 in long counts as 6 ft (§2.12.1.7).
- Hardwood surface measure: the full width in inches × the standard length in feet ÷ 12, rounded to the nearest whole square foot (Handbook 130 §2.12.1.4). AHEC’s worked example is a board 2 in thick, 6 1/4 in wide and 8 ft long: the surface measure of 4 1/6 rounds to 4, so the tally is 8 board feet, where the exact arithmetic here gives 8.333.
- Export tallies: AHEC rounds random widths to the nearest inch, alternating up and down for exact half inches, and rounds lengths down to the whole foot.
- Softwood measured with a board rule on dressed widths: fractions below the half foot are dropped and fractions above it count as the next foot (PS 20-25 §4.3).
- Thin stock: PS 20-25 §2.2 multiplies “the nominal thickness in inches or fraction of an inch” and sets no floor in that clause. Its §4.4, though, computes the average width of lumber “of nominal 1 inch or less thickness” by dividing the total board feet by the total length in feet and multiplying by 12, which gives the true width only if such lumber is tallied as 1 inch thick: a 1/2 × 6 in × 8 ft board counted at 1/2 inch is 2 board feet, and 2 ÷ 8 × 12 = 3 inches, not 6. At least one hardwood seller’s published calculator (Hardwood Industries, hardwoodind.com/bfcalc/, read 2026-09-29) rounds any thickness under 4/4 up to 4/4, and other thicknesses up to the next quarter inch. This calculator counts the thickness you enter; to match a 1-inch tally, enter 1 inch, or 4 in quarters.
Volume and board feet
PS 20-25 (Appendix B1) cautions to take great care when converting board feet, based on nominal cross-sections, to a volume of lumber based on dressed cross-sections, and quotes IEEE/ASTM SI 10: “board foot” is not a well-defined unit of volume. So the volume shown here is board feet ÷ 12 at the sizes you entered. On nominal sizes it is a nominal volume; the dressed boards hold less wood. PS 20-25 §4.1 uses dressed sizes when lumber is measured by cubic measure, so for the volume of the wood itself, enter the dressed sizes and read the volume, not the board feet.
What is deliberately not here
No price and no waste or overage figure, and no default for either: both are yours to enter, and the tool works without them. No log scale: it counts sawn lumber, not the lumber a log might yield. No weight, which depends on species and moisture. No tally rounding, and no conversion from nominal to dressed size.
Ten 2x4s, 8 ft long
No price is used: the board feet are the same whatever you pay.
- Nominal size
- 2 in × 4 in (a 2x4)
- Length
- 8 ft
- Pieces
- 10
- 01Board feet per piece= 2 × 4 × 8 ÷ 12= 5.333 bd ft
- 02Board feet for ten= 2 × 4 × 8 ÷ 12 × 10= 53.333 bd ft
- 03Linear feet= 8 × 10= 80 ft
- 04Volume at the nominal size= 53.333 ÷ 12= 4.444 cu ft (nominal)
- 05For contrast, one piece at the dressed 1 1/2 × 3 1/2 in size= 1.5 × 3.5 × 8 ÷ 12= 3.5 bd ft, which is not how PS 20-25 counts it
53.33 bd ft in 80 linear ft
Board feet per piece, common nominal sizes
Each cell is thickness × width × length ÷ 12 on the nominal size, the way PS 20-25 counts board measure. The sizes and their minimum dressed dry sizes are from PS 20-25, Table 3.
| Nominal size | Dressed dry (in) | 8 ft | 10 ft | 12 ft | 16 ft | Per linear ft |
|---|---|---|---|---|---|---|
| 1x4 | 3/4 × 3 1/2 | 2.667 | 3.333 | 4 | 5.333 | 0.333 |
| 1x6 | 3/4 × 5 1/2 | 4 | 5 | 6 | 8 | 0.5 |
| 1x8 | 3/4 × 7 1/4 | 5.333 | 6.667 | 8 | 10.667 | 0.667 |
| 1x10 | 3/4 × 9 1/4 | 6.667 | 8.333 | 10 | 13.333 | 0.833 |
| 1x12 | 3/4 × 11 1/4 | 8 | 10 | 12 | 16 | 1 |
| 2x4 | 1 1/2 × 3 1/2 | 5.333 | 6.667 | 8 | 10.667 | 0.667 |
| 2x6 | 1 1/2 × 5 1/2 | 8 | 10 | 12 | 16 | 1 |
| 2x8 | 1 1/2 × 7 1/4 | 10.667 | 13.333 | 16 | 21.333 | 1.333 |
| 2x10 | 1 1/2 × 9 1/4 | 13.333 | 16.667 | 20 | 26.667 | 1.667 |
| 2x12 | 1 1/2 × 11 1/4 | 16 | 20 | 24 | 32 | 2 |
| 4x4 | 3 1/2 × 3 1/2 | 10.667 | 13.333 | 16 | 21.333 | 1.333 |
| 6x6 | 5 1/2 × 5 1/2 | 24 | 30 | 36 | 48 | 3 |
Board feet, to three decimals. The dressed column is the minimum dressed size for dry lumber in PS 20-25, Table 3 (timbers of 5 and 6 in are printed there as 1/2 in off each way); it is shown for comparison and does not enter the board feet. Surfaced hardwood sold in stock widths uses the same nominal labels: NIST Handbook 130-2026 (§2.12.3.3, Table 2) lists every 1 in and 2 in row above with the same minimum sizes. Rough hardwood is tallied by its thickness in quarters: use the quarters mode above.
What it assumes
- 01You enter the sizes your seller tallies: nominal for softwood boards and dimension lumber, rough thickness for hardwood.
- 02Every piece on one size line has the same thickness, width and length.
- 03Length is the piece length as entered, with no trim allowance and no rounding to a standard length.
- 04An overage is added only if you enter one, and a price is applied only if you enter one. A price per MBF is a price per 1,000 board feet.
What it does not do
- It applies no seller or grading-rule rounding to thickness, width or length, so a trade tally can differ slightly.
- It does not convert nominal sizes to dressed sizes. The reference table lists the PS 20-25 minimum dressed dry size of each common size.
- It is not a log scale, and it does not measure live-edge slabs or tapered boards; for those, measure an average width yourself.
- Dimensions are entered as decimals: 8 1/4 is entered as 8.25.
- At most four sizes at once. For more, split the list and add the totals.
- It gives no weight, which depends on species and moisture content.
Common questions.
- How do you calculate board feet?
- Multiply the thickness in inches by the width in inches by the length in feet, divide by 12, and multiply by the number of pieces. With all three dimensions in inches, divide by 144 instead. An 8 ft 2x4 is 2 × 4 × 8 ÷ 12 = 5.333 board feet.
- What is a board foot?
- A volume of 144 cubic inches: a board 1 ft long, 1 ft wide and 1 in thick, or its equivalent (NIST Handbook 130-2026, §2.12.1.1). It is the unit lumber is tallied in, and it is counted on nominal sizes, which is why a board foot of dressed softwood holds less than 144 cubic inches of wood.
- Do you use nominal or actual dimensions for board feet?
- Nominal. PS 20-25 counts board feet from the nominal thickness and width (§2.2), and a nominal size is larger than the dressed size: a dry 2x4 is surfaced to 1 1/2 by 3 1/2 inches (§2.16). Enter 2 and 4 for a 2x4. Hardwood is described by its rough thickness in quarters; ask whether your seller tallies it rough or surfaced, and enter that.
- How many board feet are in a 2x4x8?
- 5.333: 2 × 4 × 8 ÷ 12 = 64 ÷ 12. A 2x6x8 is exactly 8 (96 ÷ 12), and a 4x4x8 is 10.667 (128 ÷ 12). The reference table on this page lists the common sizes at 8, 10, 12 and 16 ft.
- What do 4/4, 5/4 and 8/4 mean?
- Thickness in quarters of an inch, the way rough-sawn hardwood is described: 4/4 is 1 inch, 5/4 is 1 1/4, 6/4 is 1 1/2 and 8/4 is 2 inches (American Hardwood Export Council). Divide the top number by 4. The quarters are the rough thickness: surfaced on two sides, 4/4 is 13/16 inch in the Wood Handbook’s Table 6-4.
- What is the difference between board feet and linear feet?
- A linear foot is a foot of length, whatever the size of the piece; a board foot is a measure of volume on the sizes tallied. Board feet per linear foot = thickness × width ÷ 12, so a 2x6 is exactly 1 board foot per linear foot and a 2x4 is 0.667. NIST Handbook 130-2026 lets retail softwood be described by the number of pieces with the length of each piece or the lineal footage (§2.10.3), so a store may not show board feet at all. This calculator gives both.
- How do I price lumber by the board foot or by the MBF?
- Multiply the board feet by the price per board foot. MBF means a thousand board feet (“M” is thousand in PS 20-25, Appendix C), so a price per MBF divided by 1,000 is the price per board foot. Enter your supplier’s price in either unit under Price; the calculator suggests none.
- How many board feet are in a cubic foot?
- Twelve, at the dimensions measured: a cubic foot is 1,728 cubic inches and a board foot is 144. The catch is which dimensions. Board feet are counted on nominal sizes, so 12 board feet of dressed lumber hold less than a cubic foot of wood, and PS 20-25 (Appendix B1) cautions to take great care when converting nominal board feet to a volume of dressed lumber for that reason.
- Is lumber under 1 inch thick counted as 1 inch?
- It depends on the seller, and the sources reviewed point toward 1 inch. PS 20-25 multiplies the nominal thickness “in inches or fraction of an inch” (§2.2) and sets no floor in that clause, but its rule for the average width of lumber “of nominal 1 inch or less thickness”, board feet ÷ length in feet × 12 (§4.4), gives the true width only if that lumber is tallied as 1 inch thick. At least one hardwood seller’s published calculator counts anything under 4/4 as 4/4. This calculator uses the thickness you enter, so a 1/2 × 6 in × 8 ft board is 2 board feet here and 4 at a 1-inch tally. To match a 1-inch tally, enter 1 inch, or 4 in quarters.
- Why doesn’t my supplier’s tally match this calculator?
- Tallies round, and this calculator does not. For hardwood sold at retail, NIST Handbook 130-2026 rounds a fractional length down to the next standard length (a 6 ft 8 in board counts as 6 ft) and rounds surface measure to the nearest square foot. AHEC’s example board, 2 in × 6 1/4 in × 8 ft, tallies 8 board feet where the exact arithmetic gives 8.333. Check too whether the seller used nominal, rough or surfaced sizes.
Where people go next
Ordered by what usually comes next in the same job, not by keyword.