How to Calculate Board Feet
Use the classic lumber board-foot formula.
Quick answer
Board feet per piece = (T″ × W″ × L′) / 12. Multiply by quantity. Use the sizes you are buying (nominal vs actual).
Formula
BF = T × W × L / 12. Total BF = BF × qty.
Units
Thickness and width in inches; length in feet. For length in inches, use BF = T × W × L_in / 144.
Step-by-step
- List each line: thickness, width, length, quantity.
- Decide nominal vs actual dimensions per your price quote.
- Compute BF per piece, then extend by quantity.
- Sum the takeoff; add kerf/waste separately if cutting many pieces from longer stock.
Example — ten 2×6×10 (nominal)
Per piece: (2 × 6 × 10)/12 = 10 BF. Ten pieces = 100 BF.
Example — actual 1.5″ × 5.5″ × 8′ , qty 6
Per piece: (1.5 × 5.5 × 8)/12 = 5.5 BF. Six pieces = 33 BF. Nominal 2×6×8 would have been 8 BF each (48 BF) — know which basis your yard uses.
Quick BF for one piece (nominal)
| Size | 8 ft | 10 ft | 12 ft |
|---|---|---|---|
| 1×4 | 2.67 | 3.33 | 4.00 |
| 1×6 | 4.00 | 5.00 | 6.00 |
| 2×4 | 5.33 | 6.67 | 8.00 |
| 2×6 | 8.00 | 10.00 | 12.00 |
| 2×10 | 13.33 | 16.67 | 20.00 |
Common mistakes
- Mixing nominal pricing with actual dimensions in the same takeoff.
- Using length in inches inside the /12 formula.
Practical notes
- Hardwood often sold by board foot with grading rules — softwood framing may be by stick count.
- Kerf waste is not in the BF formula.
Related calculator
Use the free Board Foot Calculator to run the same math with your field numbers.
Related tools
- Board Foot Calculator — Lumber board feet, linear feet, and volume from dimensions.
- Feet & Fraction Calculator — Add, subtract, multiply, and divide construction measurements.
Related guides
- Feet, Inches, and Fraction Math on the Job — Add and subtract construction measurements without decimal mistakes.
FAQ
Does board foot equal cubic foot?
One board foot is 144 in³ — 1/12 of a cubic foot.
Updated 2026-09-17. Planning aid only — verify against local codes and professional judgment.