Board foot calculator
Get the board feet, linear feet and cost of a lumber order, with the actual dressed size of standard sizes such as a 2x4.
Sizes are nominal: a 2x4 is entered as 2 by 4.
For 8 ft 6 in, type 8.5.
Lumber volume
- Board feet
- 53.33 bd ft5.33 bd ft per piece
- Total length
- 80 ft
- Actual size, dry
- 1½ × 3½ in2.92 cu ft of wood at this size
Cost
From the shelf tag or the yard quote. Leave empty to skip the cost.
- Total cost
- –
- Per piece
- –
- Per linear foot
- –
Estimate only. Check product labels and local building rules before you buy or build.
Quick answer
A board foot is a piece of wood 1 inch thick, 12 inches wide and 1 foot long, or 144 cubic inches. Multiply the nominal thickness in inches by the nominal width in inches and the length in feet, then divide by 12: a 2x4 that is 8 ft long is 2 × 4 × 8 ÷ 12 = 5.33 board feet, so ten of them are 53.33 board feet.
How to use the board foot calculator
- Pick a lumber size such as 2x4 or 2x10, or type the nominal thickness and width in inches. Use the size the lumber is sold as, not what your tape reads.
- Enter the length of each piece in feet and the number of pieces. For 8 ft 6 in, type 8.5.
- Read the total board feet, the board feet per piece and the total length in linear feet. For standard sizes you also get the actual dry size and the cubic feet of wood at that size.
- To check a price, choose whether it is quoted per board foot, per piece or per linear foot, and type it. The total cost and the other two prices appear below.
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, and divide by 12. The 12 turns inches × inches × feet into board feet, because one board foot is 1 in × 12 in × 1 ft. The American Softwood Lumber Standard (PS 20) counts board feet on the nominal thickness and width, so a 2x4 counts as 2 by 4 even though it measures less.
For an order, work out one piece and multiply by the number of pieces. The total length in linear feet is the length of one piece times the count, and the price per board foot is the price of one piece divided by its board feet.
board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12total board feet = board feet per piece × number of piecesprice per board foot = price per piece ÷ board feet per piece1 board foot = 144 in³ = 1/12 ft³ = 0.00236 m³Nominal and actual lumber sizes with board feet
Actual sizes are the minimum dressed sizes for dry softwood lumber (19% moisture content or less) in PS 20-25, Table 3. Board feet are worked out from the nominal size, as the standard requires.
| Nominal size | Actual size, dry (in) | Board feet per foot | Board feet, 8 ft piece |
|---|---|---|---|
| 1x4 | ¾ × 3½ | 0.33 | 2.67 |
| 1x6 | ¾ × 5½ | 0.50 | 4.00 |
| 1x8 | ¾ × 7¼ | 0.67 | 5.33 |
| 1x10 | ¾ × 9¼ | 0.83 | 6.67 |
| 1x12 | ¾ × 11¼ | 1.00 | 8.00 |
| 2x4 | 1½ × 3½ | 0.67 | 5.33 |
| 2x6 | 1½ × 5½ | 1.00 | 8.00 |
| 2x8 | 1½ × 7¼ | 1.33 | 10.67 |
| 2x10 | 1½ × 9¼ | 1.67 | 13.33 |
| 2x12 | 1½ × 11¼ | 2.00 | 16.00 |
| 4x4 | 3½ × 3½ | 1.33 | 10.67 |
| 4x6 | 3½ × 5½ | 2.00 | 16.00 |
| 6x6 | 5½ × 5½ | 3.00 | 24.00 |
Timbers 5 and 6 in thick are dressed ½ in under their nominal size, so a 6x6 is 5½ × 5½ in. Green lumber under 5 in thick is dressed slightly larger than dry lumber.
Worked examples
Board feet in ten 2x4 studs, 8 ft long
Each stud is 2 × 4 × 8 ÷ 12 = 5.33 board feet, so ten studs are 53.33 board feet and 80 linear feet. Board feet are what a yard that sells by the board foot charges you for.
The studs actually measure 1½ × 3½ in, so each holds 1.5 × 3.5 × 96 = 504 cubic inches, or 0.29 cu ft of wood. The ten together hold 2.92 cu ft, which is 66% of the 4.44 cu ft that 53.33 board feet would suggest.
From price per piece to price per board foot for 2x8 joists
A deck needs twelve 2x8 joists, 12 ft long. Each is 2 × 8 × 12 ÷ 12 = 16 board feet, so the order is 192 board feet and 144 linear feet.
Say the tag reads $16.00 a piece. That is $16.00 ÷ 16 = $1.00 per board foot and $1.33 per linear foot, and the twelve joists cost $192.00. The price per board foot lets you compare a 2x8 with a 2x10 or a 16 ft length on equal terms.
Why is a 2x4 only 1½ by 3½ inches?
A 2x4 measures 1½ × 3½ in because "2 by 4" is its nominal size, the name it is sold under, and the American Softwood Lumber Standard (PS 20) sets the smaller size it is planed to. Dry dimension lumber sold as 2 in thick is at least 1½ in thick, widths of 4, 6 and 8 in are at least 3½, 5½ and 7¼ in, and boards sold as 1 in thick are at least ¾ in.
PS 20 counts board feet on the nominal size but cubic measure on the dressed size, and it warns against converting one into the other. That is why the calculator shows the actual size and its cubic feet next to the board feet. PS 20 also lets a piece of 2 in or thinner lumber be up to 3 in longer than its nominal length, so measure before you cut.
How is hardwood lumber measured?
Hardwood is sold by the board foot, and its rough thickness is written in quarters of an inch: 4/4 is 1 in, 5/4 is 1¼ in, 6/4 is 1½ in and 8/4 is 2 in, as the American Hardwood Export Council lists them. Enter those inch values as the thickness.
Hardwood grading rules assume boards of random width and length, so a stack rarely has one size. Measure each board, or group boards of the same width and length and enter each group with its count.
Questions
How many board feet are in a 2x4x8?
A 2x4 that is 8 ft long is 5.33 board feet: 2 × 4 × 8 ÷ 12 = 5.33. Board feet use the nominal size, so it does not matter that the stud measures 1½ × 3½ in. Ten of them make 53.33 board feet, and a 2x4 that is 12 ft long is 8 board feet.
How do I convert a price per piece to a price per board foot?
Divide the price of one piece by its board feet. A 2x8 that is 12 ft long holds 16 board feet, so at $16.00 a piece it costs $1.00 per board foot. To go the other way, multiply the price per board foot by the board feet in one piece. Comparing prices per board foot shows which size or length is the better buy.
What size is a 2x6 actually?
A dry 2x6 is 1½ × 5½ in, the minimum dressed size in the American Softwood Lumber Standard (PS 20). It is still counted as 2 × 6 for board feet, so a 2x6 that is 10 ft long is 2 × 6 × 10 ÷ 12 = 10 board feet. Green lumber is dressed a little larger, 1 9/16 × 5 5/8 in.
How many board feet are in a cubic meter?
One cubic meter is 423.78 board feet when the board feet are counted on the true size, because a board foot is 1/12 cu ft, or 0.00236 m³. The American Hardwood Export Council rounds this to 424. Softwood sold by nominal size gives more board feet per cubic meter of real wood, which is why PS 20 warns against mixing the two.
What does 4/4 mean for lumber?
4/4, read "four quarter", means a rough-sawn hardwood board 1 in thick. Hardwood thickness is counted in quarters of an inch, so 5/4 is 1¼ in, 6/4 is 1½ in and 8/4 is 2 in. An 8/4 board 6 in wide and 8 ft long is 2 × 6 × 8 ÷ 12 = 8 board feet.
Sources
- National Institute of Standards and Technology (published by the American Lumber Standard Committee), Voluntary Product Standard PS 20-25, American Softwood Lumber Standard (checked October 19, 2026)Board measure on nominal size (2.2), cubic measure on dressed size (4.1), dry lumber at 19% moisture (2.7), standard lengths and trim allowance (5.3), nominal and minimum dressed sizes (Table 3).
- American Hardwood Export Council, Grading sawn lumber: Measurement (checked October 19, 2026)Board foot formula, hardwood thickness in quarters of an inch, 1 m³ = 424 board feet.
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