Board Foot Calculator (Free, With Waste and Cost)
Add each board in your project and get the total board feet, a waste allowance and an estimated cost. It works on your phone at the lumber yard, and nothing you type leaves your browser.
Your boards
Price is optional: enter the dealer's price per board foot to see a cost estimate. Your list is saved in this browser only.
How to use the calculator
- Pick whether you measure length in feet or inches, and choose a waste allowance.
- For each board, enter how many you need, the thickness and width in inches and the length.
- Add the price per board foot if you know it. Leave it at 0 to skip the cost.
- Copy or print the list and take it to the lumber yard.
Not sure what parts you need yet? Start with our guide on how to make a cut list, then come back and add the boards here.
The board foot formula
One board foot is 144 cubic inches, the same as a board 1" thick, 12" wide and 12" long.
- Length in feet: board feet = thickness (in) x width (in) x length (ft) / 12
- Length in inches: board feet = thickness (in) x width (in) x length (in) / 144
Multiply by the number of pieces, then add your waste allowance.
Worked examples
| Board | Math | Board feet |
|---|---|---|
| 4/4 oak, 6" wide, 8 ft | 1 x 6 x 8 / 12 | 4.00 |
| 8/4 maple, 8" wide, 10 ft | 2 x 8 x 10 / 12 | 13.33 |
| 2x4, 8 ft (nominal size) | 2 x 4 x 8 / 12 | 5.33 |
| Three 1x12 boards, 6 ft | 3 x (1 x 12 x 6 / 12) | 18.00 |
Quarter sizes: what 4/4 and 8/4 mean
Rough hardwood is sold by thickness in quarters of an inch. The board foot math uses the rough thickness, even though the board gets thinner after planing.
| Quarter size | Rough thickness | Typical surfaced thickness |
|---|---|---|
| 4/4 | 1" | about 13/16" |
| 5/4 | 1-1/4" | about 1-1/16" |
| 6/4 | 1-1/2" | about 1-5/16" |
| 8/4 | 2" | about 1-3/4" |
| 12/4 | 3" | about 2-3/4" |
Surfaced thickness varies by mill, so measure the boards you buy. For softwood like pine, sizes such as 1x6 and 2x4 are nominal; see choosing wood for beginners for actual sizes.
Tips before you buy
- Buy the long and wide parts first, then cut small parts from what is left.
- Check each board for twist, cup and splits at the ends, and plan to trim an inch or two from each end.
- If you need matching grain for a tabletop or door panels, buy one extra board.
Board foot questions
What is a board foot?
A board foot is a unit of volume for lumber: a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Hardwood dealers usually price lumber per board foot, so you need the total to compare prices and plan a project.
How many board feet are in a 2x4x8?
Using nominal sizes, a 2x4 that is 8 feet long has 2 x 4 x 8 / 12 = 5.33 board feet. Home centers usually sell 2x4s by the piece, not by the board foot, but the number helps when you compare against lumber priced by volume.
Should I use nominal or actual sizes?
Board feet are normally figured on the nominal or rough size the lumber was sold as. A 4/4 hardwood board counts as 1 inch thick even after it is planed to about 13/16 inch. For your cut list and joinery, always use the actual measured size.
How much extra lumber should I buy?
Many woodworkers add 10 to 20 percent for surfaced boards and 25 to 30 percent or more for rough lumber, because of knots, checks, snipe and saw kerf. It depends on the boards you find and how many long or wide parts the project needs, so look at the actual boards before you decide.
What is the difference between a board foot and a linear foot?
A linear foot is just length: 12 inches of a board, no matter how thick or wide it is. A board foot is volume. A 1x12 that is one foot long is one board foot, while a 1x6 of the same length is half a board foot.
Is plywood sold by the board foot?
No. Plywood and other sheet goods are sold by the sheet. If you ever need a comparison, a 3/4 inch 4 x 8 sheet works out to 0.75 x 48 x 96 / 144 = 24 board feet.