Board Foot Calculator
Add a row per cut size. Board feet = (thickness in × width in × length ft ÷ 12) × quantity.
Code notes follow the 2021 IRC. Local codes amend it, so check your local code.
Row 1
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Nominal vs actual dimensions
| Nominal | Actual (in) |
|---|---|
| 1×2 | 0.75 × 1.5 |
| 1×4 | 0.75 × 3.5 |
| 1×6 | 0.75 × 5.5 |
| 1×8 | 0.75 × 7.25 |
| 2×4 | 1.5 × 3.5 |
| 2×6 | 1.5 × 5.5 |
| 2×8 | 1.5 × 7.25 |
| 2×10 | 1.5 × 9.25 |
| 2×12 | 1.5 × 11.25 |
| 4×4 | 3.5 × 3.5 |
What is a board foot?
A board foot is a volume unit equal to 144 cubic inches. The formula is thickness in inches times width in inches times length in feet, divided by 12, times the number of pieces.
Should I use nominal or actual size?
Use nominal for ordering and pricing. A 2x4 is sold and priced as a 2x4 even though the dressed size is 1.5 x 3.5 inches. Use actual size only when you are checking real fit.
Assumptions and sources
- Boards to buy: your cuts are nested onto standard lengths (8, 10, 12, 14, 16 ft), picking the length that wastes the least. The count already includes offcut waste. Saw kerf is not deducted.
- Pressure-treated (2021 IRC R317): wood on concrete or masonry, or within 6 in of grade, is flagged PT. Local codes amend it, so check yours.
Drafts to plan from. Confirm before you order.