Lumber Calculator — Board Feet & Lumber Cost
Enter your board size and count to get the exact board feet and total cost for your lumber order. No sign-up, no data stored.
Board feet
How board feet is calculated
The math is simple and exact — no assumptions to adjust for:
- Board foot = thickness (in) × width (in) × length (ft) ÷ 12.
- One board foot = 1 inch thick × 12 inches wide × 1 foot long (144 cubic inches).
- Total = board feet per board × number of boards.
- Cost = total board feet × price per board foot (only if you enter a price).
Lumber is priced by the nominal size (a 2×4 counts as 2×4, even though it's actually 1.5×3.5 inches). For framing and dimensional lumber, this is standard industry practice.
Lumber reference chart
Board feet for common nominal sizes at 8-foot lengths.
Common lumber sizes → board feet (8 ft)
| Nominal size | Actual size | Board feet (8 ft) |
|---|---|---|
| 1×4 | 0.75×3.5" | 2.67 |
| 1×6 | 0.75×5.5" | 4.0 |
| 1×8 | 0.75×7.25" | 5.33 |
| 2×4 | 1.5×3.5" | 5.33 |
| 2×6 | 1.5×5.5" | 8.0 |
| 2×8 | 1.5×7.25" | 10.67 |
| 4×4 | 3.5×3.5" | 10.67 |
Last updated: October 2026 · Nominal sizes are standard US lumber designations. Board foot pricing is typical for hardwoods; dimensional lumber is usually priced per piece. Always confirm with your supplier.
Lumber calculator FAQ
A 2×4×8 is 2 × 4 × 8 ÷ 12 = 5.33 board feet. It's priced by the nominal 2×4 size, not the actual 1.5×3.5 inches.
One board foot equals 1/12 of a cubic foot, so multiply board feet by 0.0833 to get cubic feet. A 12 board feet is exactly 1 cubic foot.
A linear foot is just a length of board (any width). A board foot accounts for thickness × width × length, so it measures volume. Lumber that varies in size is priced by board foot; fencing and trim often by linear foot.
Yes. Add 10–15% for cuts, defects, and mistakes, especially for projects with many angled or fitted pieces. For rough-sawn or irregular lumber, add even more.
Lumber is milled and planed down from the rough sawn size, so a nominal 2×4 ends up 1.5×3.5 inches after surfacing. You still pay for and order by the nominal size.