Board Feet Calculator
Calculate board feet of lumber needed for any woodworking project.
Board Feet Calculator
What This Calculator Does
The Board Feet Calculator determines the volume of lumber in board feet - the standard unit for buying and selling lumber in the US. Enter the thickness, width, and length of a board (or multiple boards) to get the total board footage instantly.
One board foot equals 144 cubic inches (12 in x 12 in x 1 in). Lumber yards and home centers price dimensional lumber by the board foot, making this calculation essential for any woodworking, framing, or decking project. A 2x4x96-inch stud contains 5.33 board feet. At current lumber prices of approximately $1.20-$1.80 per board foot, knowing the board footage helps prevent both shortages and costly overages.
Use this calculator for any dimensional lumber: studs, joists, rafters, deck boards, or hardwood lumber. The calculator also shows the per-board board footage so you can understand the unit pricing regardless of board dimensions.
How to Use
- Measure the thickness, width, and length of your lumber in inches. For US dimensional lumber, use nominal dimensions (e.g., a 2x4 actually measures 1.5 x 3.5 inches).
- Enter the thickness in inches, width in inches, and length in inches.
- Enter the quantity of identical boards.
- Click "Calculate" to see the total board feet and per-board board footage.
- Multiply total board feet by the price per board foot from your supplier to get the lumber cost.
Worked Examples
Deck Board Material Takeoff
A 12 x 16 ft deck using 2x6 treated lumber for the decking surface, boards laid perpendicular to the 16-ft joists.
- →Deck width = 12 ft = 144 in. Each 2x6 (actual 5.5 in wide) laid with 1/8-in gap: effective coverage 5.375 in per board. Boards needed: 144 / 5.375 = 26.8, round up to 27 boards.
- →Each board is 16 ft long = 192 in. Board feet per board: (1.5 in x 5.5 in x 192 in) / 144 = 11 BF.
- →Total board feet: 27 boards x 11 BF = 297 BF.
- →Add 10% waste for trimming ends and cutting around obstructions: 297 x 1.10 = 327 BF.
- →At $1.50 per BF for treated 2x6: 327 x $1.50 = $491 estimated lumber cost.
Result: Approximately 327 board feet of 2x6 treated lumber needed for a 12x16 ft deck surface, costing about $490.
Order 2x6 boards in 16-ft lengths to avoid end-joins on the deck surface. Fewer joints mean faster installation, less waste, and a cleaner finished appearance.
Reference Table
| Lumber Size | Actual Size (in) | Board Feet per LF | Common Use |
|---|---|---|---|
| 2x4 | 1.5 x 3.5 | 0.036 BF per in | Studs, plates, blocking |
| 2x6 | 1.5 x 5.5 | 0.057 BF per in | Joists, rafters, headers |
| 2x8 | 1.5 x 7.25 | 0.076 BF per in | Floor joists, beams |
| 2x10 | 1.5 x 9.25 | 0.096 BF per in | Roof rafters, floor joists |
| 4x4 | 3.5 x 3.5 | 0.085 BF per in | Posts, columns |
| 4x6 | 3.5 x 5.5 | 0.134 BF per in | Beams, heavy posts |
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