Board Feet Chart: How to Calculate Board Feet of Lumber
A board foot is a piece of wood 1 inch thick, 12 inches wide and 1 foot long, which is 144 cubic inches. To find the board feet of a board, multiply the thickness (in) × width (in) × length (ft) ÷ 12. An 8 foot 2×4 is 2 × 4 × 8 ÷ 12 = 5.33 board feet. Use the nominal size (the size the board is called). The board foot calculator adds up a whole order and works out the cost.
Board feet in common boards
By nominal size and length:
| Board | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1 × 4 | 2.67 | 3.33 | 4.00 | 5.33 |
| 1 × 6 | 4.00 | 5.00 | 6.00 | 8.00 |
| 1 × 8 | 5.33 | 6.67 | 8.00 | 10.67 |
| 1 × 12 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 4 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2 × 6 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 8 | 10.67 | 13.33 | 16.00 | 21.33 |
| 2 × 10 | 13.33 | 16.67 | 20.00 | 26.67 |
| 2 × 12 | 16.00 | 20.00 | 24.00 | 32.00 |
| 4 × 4 | 10.67 | 13.33 | 16.00 | 21.33 |
| 6 × 6 | 24.00 | 30.00 | 36.00 | 48.00 |
Cost by price per board foot
Ten boards of 1 × 6 × 8 ft (40 board feet) and ten 2 × 4 × 8 ft (53.3 board feet):
| Price per board foot | Ten 1×6×8 | Ten 2×4×8 |
|---|---|---|
| $3 | $120 | $160 |
| $4 | $160 | $213 |
| $6 | $240 | $320 |
| $8 | $320 | $427 |
| $12 | $480 | $640 |
Where board feet are used
- Hardwood lumber (oak, walnut, maple, cherry) is almost always sold by the board foot, so that thick and thin boards compare fairly.
- Rough or custom-milled lumber and slabs for tables are priced by the board foot too.
- Construction lumber (2×4s, 2×6s) is sold by the piece or the linear foot at a home center, but board feet are handy for comparing the cost of different sizes.
Tips
- For boards of unequal width, measure the average width. For a tapered board, use the average of the two ends.
- Buy 10 to 15% more than the board feet you need, since cuts, knots and defects waste some, and hardwood often needs more.
- Rough lumber is thicker than finished lumber: ask the supplier how the thickness is counted (4/4 means 1 inch rough).
- If you need a cost per piece, multiply the board feet in one piece by the price per board foot.
For the actual sizes of lumber, see the lumber size chart, and use the stud calculator and the deck board calculator to count boards for a job.
Frequently asked questions
How do you calculate board feet?
Multiply the thickness in inches by the width in inches by the length in feet, and divide by 12. A 2 × 4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet.
How many board feet are in a 2x4?
An 8 foot 2×4 is 5.33 board feet, a 10 foot is 6.67, a 12 foot 8.00 and a 16 foot 10.67.
How many board feet are in a 1x6x8?
4 board feet. A 1 × 6 is a half board foot per foot of length.
What is a board foot?
A volume of lumber of 144 cubic inches: a board 1 inch thick, 12 inches wide and 12 inches (1 foot) long. Hardwood and many rough boards are sold by the board foot.
Do I use nominal or actual size to calculate board feet?
Nominal size: lumber is priced by the board foot using the size that it is called (a 2×4 counts as 2 inches by 4 inches), even though the actual size is 1½ by 3½ inches.
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and follow local building codes for anything structural.