Board Foot Calculator
This board foot calculator converts a stack of lumber into board feet — the volume measure sawmills and hardwood dealers price by. Pick a nominal size like 2×6 and it uses the actual milled dimensions automatically, or switch to actual mode and type the exact thickness and width. Works in feet and inches or meters and millimeters, and totals the cost when you add a price per board foot.
Total board feet
99board feet
- Board feet per piece8.25 bd ft
- Actual dimensions used1.5″ × 5.5″
Formulas last reviewed on .
How board feet are calculated
A board foot is a volume: 144 cubic inches of wood, or a piece one foot square and one inch thick. The formula mixes units on purpose, because that’s how lumber is measured in the yard:
Thickness and width go in as inches, length in feet, and the ÷12 reconciles the mismatch. A 12-foot 2×6 works out to 1.5 × 5.5 × 12 ÷ 12 = 8.25 board feet.
Note the 1.5 and 5.5 — a “2×6” hasn’t measured 2 by 6 inches since before it was dried and planed. This calculator prices the wood that actually goes on your truck, so nominal sizes are converted to actual milled dimensions using the table below. Switch to actual mode to enter rough-sawn or hardwood dimensions directly.
| Nominal | Actual (in) | Nominal | Actual (in) |
|---|---|---|---|
| 1×2 | 0.75 × 1.5 | 2×2 | 1.5 × 1.5 |
| 1×3 | 0.75 × 2.5 | 2×3 | 1.5 × 2.5 |
| 1×4 | 0.75 × 3.5 | 2×4 | 1.5 × 3.5 |
| 1×6 | 0.75 × 5.5 | 2×6 | 1.5 × 5.5 |
| 1×8 | 0.75 × 7.25 | 2×8 | 1.5 × 7.25 |
| 1×10 | 0.75 × 9.25 | 2×10 | 1.5 × 9.25 |
| 1×12 | 0.75 × 11.25 | 2×12 | 1.5 × 11.25 |
| 4×4 | 3.5 × 3.5 | 6×6 | 5.5 × 5.5 |
Worked example: a dozen 2×6s for a pergola
Say you’re pricing the overhead lumber for a backyard pergola: twelve 2×6 rafters, each 12 feet long. That’s exactly what the calculator loads by default, so you can follow along in the result box above.
- Actual dimensions: a nominal 2×6 mills out at 1.5″ thick × 5.5″ wide.
- Per piece: 1.5 × 5.5 × 12 ÷ 12 = 8.25 board feet in each rafter.
- Project total: 8.25 × 12 pieces = 99 board feet.
- Cost check: punch a price into the advanced field to see the damage — at $0.85 per board foot, this stack runs 99 × 0.85 = $84.15. Leave the price at zero and the cost line stays out of the way.
The same three steps work for any pile of lumber. Where board feet really earn their keep is comparing quotes: a supplier asking $1.10 per board foot for 2×8s wants $9.97 for a 10-foot stick (9.06 bd ft), so a second yard quoting $9.50 per board is actually about a nickel per board foot cheaper — and this math is the only way to see it.
How many board feet are in a 2×4, 2×6, or 2×12?
The table below covers the sizes stocked at any lumberyard, at the four most common lengths. Every figure is computed from actual milled dimensions with the formula above — multiply by your piece count and you’ve got a project total.
| Size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1×4 | 1.75 | 2.19 | 2.63 | 3.5 |
| 1×6 | 2.75 | 3.44 | 4.13 | 5.5 |
| 2×4 | 3.5 | 4.38 | 5.25 | 7 |
| 2×6 | 5.5 | 6.88 | 8.25 | 11 |
| 2×8 | 7.25 | 9.06 | 10.88 | 14.5 |
| 2×10 | 9.25 | 11.56 | 13.88 | 18.5 |
| 2×12 | 11.25 | 14.06 | 16.88 | 22.5 |
| 4×4 | 8.17 | 10.21 | 12.25 | 16.33 |
Two boards of the same length can differ by a factor of six: an 8-foot 1×4 is 1.75 board feet while an 8-foot 2×12 is 11.25. That’s why “how much for a board?” is a meaningless question at a hardwood dealer — volume is everything.
Frequently asked questions
What’s the difference between a board foot and a linear foot?
A linear foot measures length only — 8 feet of 2×4 and 8 feet of 2×12 are both 8 linear feet. A board foot measures volume, so those same two boards are 3.5 and 11.25 board feet. Suppliers price studs and decking by the piece or linear foot because the cross-section is fixed; board feet take over whenever sizes are mixed, which is why hardwood and sawmill lumber are quoted that way.
Should I use nominal or actual dimensions to calculate board feet?
This calculator uses actual milled dimensions, so the total reflects wood you can measure with a tape. Be aware that the older trade convention tallies on nominal size — counted that way, an 8-foot 2×4 is 5.33 board feet instead of 3.5. If a mill quotes you “per board foot, nominal measure,” expect their tally to run higher than this page’s. Same wood, two bookkeeping systems; just make sure the quote and the count use the same one.
How does hardwood pricing by the board foot work?
Hardwood dealers sell rough stock measured in quarters of an inch: 4/4 is one inch thick, 8/4 is two. You pay on the rough dimensions even if the dealer surfaces the board down to 13/16″ for you, so a 4/4 board 6″ wide and 8 feet long is billed as 4 board feet regardless of what it measures after planing. For rough hardwood, switch this calculator to actual mode and enter the rough thickness and width.
How do I total board feet for a whole project cut list?
Group the list by size and length, then run each group through the calculator: pick the size, enter the length, and set the number of pieces to the group’s count. Jot down each total and add them up. For the pergola example, twelve 12-foot 2×6s (99 bd ft) plus four 10-foot 4×4 posts (40.83 bd ft) comes to roughly 140 board feet — multiply by your dealer’s rate and you’ve priced the frame before leaving the couch.
How many board feet are in an 8-foot 2×4?
Using actual dimensions — 1.5″ × 3.5″ — an 8-foot 2×4 contains 3.5 board feet. Counted on nominal measure (2″ × 4″) it would be 5.33. The gap between those two numbers is exactly why this calculator shows you the actual dimensions it used in the results: when a price seems too good, check which measure the seller is counting.
These results are planning estimates only — verify quantities with your supplier and local building code before you buy or build. See our terms of use.