Many lumber yards price sawn wood by the board foot, a unit of volume rather than length. One board foot is 144 cubic inches of wood: a board one foot long, one foot wide and one inch thick, or the same volume in another shape.
How to use this calculator
- Enter the nominal thickness and width in inches. For a 2x4, the first number is the thickness and the second is the width.
- Enter the length of one piece in feet, as the yard sells it. Do not subtract cuts, because the calculator counts whole pieces at the length you give.
- Set the pieces to the number of boards of that size and length. Add a few spares for defects and cut-offs, since the calculator counts only the boards you enter. If you are buying framing for a wall, count the studs with the stud calculator first.
- Read the board feet from the result. The per-piece figure checks one board, and the total covers the whole order.
- If the yard has quoted a price per board foot, open More options and enter it. The result then shows the cost at that price for the pieces you entered.
Worked examples
Framing lumber
Thickness: 2 in · Width: 4 in · Length: 8 ft · Pieces: 10
- Board feet
- 53.33 board ft
- Per piece
- 5.33 board ft
- Total length
- 80 linear ft
Deck boards
Thickness: 1.25 in · Width: 6 in · Length: 12 ft · Pieces: 20
- Board feet
- 150.00 board ft
- Per piece
- 7.50 board ft
- Total length
- 240 linear ft
Pine shelving
Thickness: 1 in · Width: 12 in · Length: 6 ft · Pieces: 4
- Board feet
- 24.00 board ft
- Per piece
- 6.00 board ft
- Total length
- 24 linear ft
Hardwood workbench
Thickness: 2 in · Width: 6 in · Length: 8 ft · Pieces: 6
- Board feet
- 48.00 board ft
- Per piece
- 8.00 board ft
- Total length
- 48 linear ft
Board feet for one board of common nominal sizes
| Nominal thickness, width (in) | Length: 8 ft | Length: 12 ft | Length: 16 ft |
|---|---|---|---|
| 1 × 4 in | 2.67 | 4.00 | 5.33 |
| 1 × 6 in | 4.00 | 6.00 | 8.00 |
| 1 × 12 in | 8.00 | 12.00 | 16.00 |
| 2 × 4 in | 5.33 | 8.00 | 10.67 |
| 2 × 6 in | 8.00 | 12.00 | 16.00 |
| 2 × 10 in | 13.33 | 20.00 | 26.67 |
Each cell: Board feet (board ft). Inputs not in the table use the calculator's starting values.
The formula, step by step
The calculator multiplies the thickness, the width and the length, with the length converted to inches, and divides by 144 cubic inches. That gives the board feet for one piece. Multiply by the number of pieces for the total.
Total length is the length of one piece times the number of pieces, in linear feet. Use it when a supplier sells by the linear foot.
Nominal sizes and hardwood thickness
A 2x4 is counted at its nominal thickness and width, even though it measures less once it is dressed (planed smooth at the mill). For decking, start with the deck calculator to size the surface, then count the boards here.
Hardwood is often sold by the board foot, with thickness stated in quarters of an inch. Convert it to inches before you enter it, and ask the seller if you are unsure.
Pricing a load of lumber
To price a load, run the calculator once for each size and length on the order. Enter the price per board foot under More options, read the cost for each line, and add the lines together. Each cost is that line's board feet times the price, so you can check a line by hand.
Check the unit before you enter a price. Some yards quote a bulk price per MBF, which means per thousand board feet. Convert that to a price for one board foot first, because the calculator expects a price for each board foot.
The cost covers the lumber you enter and nothing else. Delivery, sales tax and any boards you plan to waste are not included, so add them yourself.
Mistakes to avoid
- Entering the size from a tape measure. Use the nominal size, because board feet are based on it.
- Mixing up board feet and linear feet. Linear feet count only length, so a yard that sells by the board foot prices in thickness and width too.
- Using the result for a standing tree or a log. This calculator measures sawn boards. Estimating the board feet in a log uses separate log rules, which this page does not cover.
What do the quarter sizes of hardwood lumber mean?
Rough hardwood thickness is counted in quarters of an inch, so the top number is how many quarters thick the board is. Four-quarter stock is 1 inch thick, five-quarter is 1.25 inches, six-quarter is 1.5 inches, and eight-quarter is 2 inches. Those are rough sizes, so ask the seller whether the board has been planed, because planing makes it thinner.
Common questions
How do I convert board feet to square feet?
You cannot convert them directly, because board feet measure volume and square feet measure area. For a board of a given nominal thickness, divide the board feet by that thickness in inches to get square feet.
How do you calculate the cubic feet of wood?
Multiply the thickness, width and length, all in inches, to get cubic inches. Divide that by the number of cubic inches in one cubic foot. Board feet divide by 144 cubic inches instead, so a board foot is a much smaller amount of wood than a cubic foot.
What is the difference between board feet and linear feet?
Linear feet measure only length. Board feet also count thickness and width, so two boards of the same length can have very different board feet.
How do I work out the cost of lumber by the board foot?
Multiply the total board feet by the price per board foot the yard quotes. Enter that price under More options to see the cost. Check whether the quote is per board foot or per MBF first.
How do I convert linear feet to board feet?
Multiply the nominal thickness by the nominal width, both in inches, and divide by 12 inches. That gives the board feet in each linear foot of the board. Multiply it by the total linear feet to get the board feet.
How many board feet are in a 2x4 or a 1x12?
Multiply the nominal thickness by the nominal width, both in inches, then by the length in feet times 12 inches, and divide by 144 cubic inches. Or enter the board in the calculator above, which does the same math.