Board foot calculator
Board feet for any lumber size and quantity, figured from nominal dimensions the way a mill and a lumberyard price it. Same math the CutOnce app runs on the jobsite.
Updated
Board feet are figured from the nominal size (a 2x4 counts as 2 x 4). Pick a size to fill the nominal thickness and width, or type your own.
- Total board feet
- 5.333
What a board foot is
A board foot is the amount of lumber in a piece 1 inch thick, 12 inches wide, and 1 foot long, which is 144 cubic inches. You figure it as thickness in inches times width in inches times length in feet, divided by 12, using the nominal size. A 2x8 that is 12 feet long is 2 times 8 times 12, divided by 12, which is 16 board feet.
A worked example
A single 2x8 at 12 ft. The board feet are computed by the same function that drives the calculator above.
| Nominal thickness | 2 in |
| Nominal width | 8 in |
| Length | 12 ft |
| Board feet | 16.000 |
Board feet per foot, by nominal size
Board feet are always figured from the nominal size, but a board is milled smaller: a 2x4 really measures 1-1/2 by 3-1/2 inches once it is dressed. Buy and price by the board foot on the left; cut and fit to the actual size on the right.
| Nominal | Actual (dressed) | Board feet per ft |
|---|---|---|
| 1x4 | 0.75 x 3.5 in | 0.333 |
| 1x6 | 0.75 x 5.5 in | 0.500 |
| 1x8 | 0.75 x 7.25 in | 0.667 |
| 2x4 | 1.5 x 3.5 in | 0.667 |
| 2x6 | 1.5 x 5.5 in | 1.000 |
| 2x8 | 1.5 x 7.25 in | 1.333 |
| 2x10 | 1.5 x 9.25 in | 1.667 |
| 2x12 | 1.5 x 11.25 in | 2.000 |
| 4x4 | 3.5 x 3.5 in | 1.333 |
| 6x6 | 5.5 x 5.5 in | 3.000 |
How to figure board feet
- 01
Use the nominal size
Board feet are a billing unit, not a measurement of the dressed board, so a 2x4 counts as a full 2 by 4 even though it dresses to 1-1/2 by 3-1/2. That is the number the yard charges against.
- 02
Multiply thickness, width, and length
Thickness in inches times width in inches times length in feet, then divide by 12. The 12 is there because a 1-by-12 one foot long is exactly one board foot, so the formula scales from that.
- 03
Multiply by the count
One 2x8 at 12 ft is 16 board feet, so 30 of them is 480. Enter a quantity and the calculator carries the multiply and shows the per-piece figure too, which is what you check a price quote against.
Common questions
- What is the board foot formula?
- Thickness in inches times width in inches times length in feet, divided by 12. Equivalently, thickness times width times length all in inches, divided by 144. Both give the same number; use whichever matches how your length is measured.
- Do I use nominal or actual size?
- Nominal, always, for buying and pricing. Board feet are how lumber is sold, and the trade quotes the nominal size. The actual dressed size (a 2x4 is 1-1/2 by 3-1/2) matters when you are fitting the board, not when you are counting board feet.
- What is MBF?
- MBF is a thousand board feet, the unit lumber is often priced in at wholesale. A price of $600 per MBF is 60 cents per board foot, so your 480 board feet of 2x8 would run about $288 at that rate.
- How is this different from a linear or square foot?
- A linear foot only counts length, and a square foot only counts area, but a board foot counts volume, so it captures thickness too. That is why a 2x8 and a 1x8 of the same length are different board feet but the same linear feet.
Price the whole list, offline
The app totals board feet across a full lumber list, prices it per board foot or per MBF, and works with no signal. Part of the one-time toolbox, no subscription.
See also