Lumber Board Feet Calculator
Calculate board feet of lumber from thickness, width and length, plus total footage and cost. Free board foot calculator with the formula and worked example shown.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Board Feet Calculator Works
This calculator finds the board footage of lumber from its thickness, width, and length, then multiplies by the number of pieces and an optional price per board foot to estimate total volume and cost. Enter the length in either feet or inches and the tool converts it for you.
Board feet are the standard way rough and hardwood lumber is sold in the United States, so getting the count right is essential for ordering material and budgeting a project.
The Formula
Board feet = (thickness in × width in × length in) ÷ 144
One board foot equals 144 cubic inches (a piece 12 in × 12 in × 1 in), so dividing total cubic inches by 144 gives board feet. If you prefer to measure length in feet, an equivalent form is:
Board feet = (thickness in × width in × length ft) ÷ 12
To get your total, multiply board feet per piece by the number of pieces, and multiply that total by the price per board foot for the cost.
Worked Example
Take a board that is 2 in thick, 6 in wide, and 8 ft (96 in) long, and you need 10 of them at $4.50 per board foot:
- Board feet per piece = (2 × 6 × 96) ÷ 144 = 1152 ÷ 144 = 8 BF
- Total board feet = 8 × 10 = 80 BF
- Estimated cost = 80 × $4.50 = $360.00
Common Board Foot Quantities
| Board (T × W × L) | Board feet each |
|---|---|
| 1 in × 6 in × 8 ft | 4 BF |
| 2 in × 4 in × 8 ft | 5.33 BF |
| 2 in × 6 in × 8 ft | 8 BF |
| 2 in × 8 in × 10 ft | 13.33 BF |
Tips for Accurate Estimates
- Use the dimensions you are billed for — usually rough or nominal thickness and width before surfacing.
- Round up your order to allow for waste, defects, and cutting; many woodworkers add 10 to 20%.
- Check the price unit — hardwood is sold per board foot, but some dimensional softwood is sold per linear foot or per piece.
Frequently asked questions
How do you calculate board feet?+
Multiply the thickness, width and length all in inches, then divide by 144, because one board foot equals 144 cubic inches. A board 2 in thick, 6 in wide and 96 in (8 ft) long is (2 × 6 × 96) ÷ 144 = 8 board feet.
What is a board foot?+
A board foot is a unit of lumber volume equal to 144 cubic inches, the volume of a piece one foot long, one foot wide and one inch thick. It is the standard way hardwood lumber is sold and priced in the United States.
Why divide by 144 for board feet?+
One board foot is 12 in × 12 in × 1 in = 144 cubic inches. Dividing the total cubic inches of your board by 144 converts the volume into board feet. If you measure length in feet instead, the formula becomes (thickness in × width in × length ft) ÷ 12.
Do I use nominal or actual dimensions?+
Hardwood board feet are normally figured from the rough or nominal thickness and width before final surfacing, since that is the material you pay for. Use the dimensions your supplier quotes; for surfaced softwood, nominal sizes (like a 2x4) differ from actual sizes.
How do I estimate the cost of lumber?+
Multiply the total board feet by the price per board foot. If you need 80 board feet at $4.50 per board foot, the cost is 80 × 4.50 = $360. This calculator does that for you once you enter a price.