Lumber Board Feet & Timber Volume Calculator
Work out board feet for hardwood or softwood, with a waste allowance, linear feet, cubic volume and the price of the whole order. Add several board sizes to a cut list and see one total.
Written by Suhaib Hassan. Dressed sizes follow American Softwood Lumber Standard PS 20. Our methodology.
A board foot is 144 cubic inches. It multiplies thickness, width and length, divides by 12 for feet of length, then applies your waste factor.
Lumber is priced by the board foot but sold by the piece. This converts between the two so you can compare quotes.
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| Board | Qty | BF | Cost |
|---|
Nominal vs actual softwood sizes
Dressed (S4S) sizes and the board feet in common lengths, using the nominal size as lumber yards do.
| Nominal | Actual dressed size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|---|
| 1 × 4 | 3/4 × 3-1/2 in | 2.67 BF | 3.33 BF | 4.00 BF | 5.33 BF |
| 1 × 6 | 3/4 × 5-1/2 in | 4.00 BF | 5.00 BF | 6.00 BF | 8.00 BF |
| 2 × 4 | 1-1/2 × 3-1/2 in | 5.33 BF | 6.67 BF | 8.00 BF | 10.67 BF |
| 2 × 6 | 1-1/2 × 5-1/2 in | 8.00 BF | 10.00 BF | 12.00 BF | 16.00 BF |
| 2 × 8 | 1-1/2 × 7-1/4 in | 10.67 BF | 13.33 BF | 16.00 BF | 21.33 BF |
| 4 × 4 | 3-1/2 × 3-1/2 in | 10.67 BF | 13.33 BF | 16.00 BF | 21.33 BF |
How board feet are calculated
A board foot is a volume of 144 cubic inches, the size of a board 1 in thick, 12 in wide and 12 in long.
Length in feet
BF = T (in) × W (in) × L (ft) ÷ 12Length in inches
BF = T × W × L (in) ÷ 144With waste
BF gross = BF net × (1 + waste ÷ 100)Quarters explained
Rough hardwood is sold by thickness in quarters of an inch: 4/4 is 1 in, 5/4 is 1.25 in, 6/4 is 1.5 in and 8/4 is 2 in. Dried and planed boards finish thinner than the rough size.
Prices are per board foot and depend on species and grade. Ask the mill whether the price is for rough or surfaced stock.
Worked examples
Illustrative orders, each checked by hand. The first is the default setup.
Twelve 1 × 8 in boards, 8 ft
4/4 hardwood at $6.50 per BF, 15% waste.
× 12 = 64.00 BF
× 1.15 = 73.60 BF
73.60 × 6.50 = $478.40
2 × 6 framing lumber
Twelve pieces, 8 ft, at $4.20 per BF, no waste.
× 12 = 96.00 BF
96 × 4.20 = $403.20
White oak, 4/4 × 8 in × 10 ft
Six boards at $8.50 per BF.
× 6 = 40.00 BF
40 × 8.50 = $340.00
What is a board foot?
- One board foot equals 144 cubic inches of wood: 1 in × 12 in × 12 in.
- Multiply thickness by width in inches and length in feet, then divide by 12.
- Add 10% to 25% for defects, cutting loss and mistakes, more for knotty or lower-grade stock.
- Multiply by the price per board foot to get the cost.
Board feet measure volume, while linear feet measure length only. Big-box stores often price framing lumber by the piece or linear foot, so convert before comparing to a sawmill's board-foot price.
By Suhaib Hassan · Reviewed 29 September 2026 · How CalculatePilot verifies formulas →
Sources
- American Lumber Standard Committee, American Softwood Lumber Standard, Voluntary Product Standard PS 20 (dressed sizes).
- National Hardwood Lumber Association (NHLA), Rules for the Measurement and Inspection of Hardwood and Cypress.
Frequently asked questions
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2 × 4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet.
Do I use nominal or actual sizes?
Lumber is priced on the nominal size, so a 2 × 4 counts as 2 × 4 inches even though it measures 1.5 × 3.5 inches. Hardwood is priced on its rough thickness in quarters. This tool follows those trade conventions.
How much waste should I allow?
About 10% for clean, straight stock and 15% for typical work. Rustic or knotty boards, short cut-offs and complex joinery can push it to 25% or more.
What is the difference between board feet and linear feet?
Linear feet count only length. Board feet count volume, so a wide thick board has more board feet than a narrow thin one of the same length.
How many board feet are in a cubic foot?
There are 12 board feet in a cubic foot, because a cubic foot is 1,728 cubic inches and a board foot is 144.
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