Board Foot Calculator
Calculate board feet of lumber from thickness, width and length for one or many pieces, plus total cost. Free board foot calculator with the formula and a worked example.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Board Foot Calculator Works
This calculator converts lumber dimensions into board feet — the volume unit hardwood and rough lumber is sold by. Enter the thickness and width in inches and the length in feet or inches. Set the number of pieces to total a whole order, and add a price per board foot to estimate cost.
The Formula
Board feet = (thickness in × width in × length in) ÷ 144
One board foot equals 144 cubic inches, the volume of a 1 ft × 1 ft × 1 in slab. If you prefer to keep the length in feet, an equivalent shortcut is:
Board feet = (thickness in × width in × length ft) ÷ 12
For a full order, multiply the per-piece board feet by the number of pieces.
Worked Example
For ten boards, each 2 in thick, 6 in wide and 8 ft long:
- Length in inches = 8 × 12 = 96 in
- Board feet per piece = (2 × 6 × 96) ÷ 144 = 8 BF
- Total = 8 × 10 = 80 board feet
At $6.50 per board foot, the cost is 80 × $6.50 = $520 before waste.
Board Foot vs Linear Foot
A linear foot counts only length, so it is fine for trim and dimensional lumber sold by the running foot. A board foot accounts for thickness and width too, which is why thicker or wider boards cost more per linear foot. When a supplier quotes a per-board-foot price, convert your cut list with the formula above before comparing prices.
Why Board Feet Matter
Pricing and buying lumber correctly depends on board feet:
- Compare prices fairly across boards of different sizes.
- Estimate project material for furniture, flooring and framing.
- Budget accurately by adding a 10 to 20 percent waste allowance for cuts and defects.
| Board (nominal) | Length | Board feet each |
|---|---|---|
| 1 × 6 | 8 ft | 4 BF |
| 2 × 4 | 8 ft | 5.33 BF |
| 2 × 6 | 8 ft | 8 BF |
| 4 × 4 | 8 ft | 10.67 BF |
Frequently asked questions
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 unit by which rough and hardwood lumber is sold and priced in the United States and Canada.
How do you calculate board feet?+
Multiply thickness, width and length all in inches, then divide by 144. A board 2 in thick, 6 in wide and 96 in (8 ft) long is (2 × 6 × 96) ÷ 144 = 8 board feet. If you measure length in feet, you can instead use (thickness in × width in × length ft) ÷ 12.
What is the difference between a board foot and a linear foot?+
A linear foot measures only length, ignoring thickness and width, while a board foot measures volume from all three dimensions. Two boards of the same length have the same linear footage but different board footage if their thickness or width differs.
Do I use nominal or actual lumber dimensions for board feet?+
Lumberyards calculate board feet using the nominal size before surfacing, so a 2x6 counts as 2 in by 6 in even though the finished board measures about 1.5 in by 5.5 in. Use nominal dimensions when pricing, and actual dimensions when planning fit.
How do I figure the cost of lumber from board feet?+
Multiply the total board feet by the price per board foot. For 80 board feet of oak at $6.50 per board foot, the cost is 80 × 6.50 = $520. Add a waste allowance of 10 to 20 percent for cutting, defects and grain matching.