Board Foot Calculator
This board foot calculator estimates lumber volume and cost using the measurement basis you choose. Select finished dimensions for actual wood volume, nominal tally to match a supplier’s quoted sizes, or custom dimensions for rough stock. Enter piece length, quantity, and an optional price per board foot. The result shows the dimensions used so you can check them against the quote.
Total board feet
99board feet
- Board feet per piece8.25 bd ft
- Actual dimensions used1.5″ × 5.5″
Updated .
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. The default mode measures finished wood volume by converting the named size to its milled dimensions using the table below. For a supplier quoting nominal board measure, choose Nominal tally from size: a 12-foot 2×6 is then 2 × 6 × 12 ÷ 12 = 12 board feet. The same board has 8.25 board feet of finished volume. Match the measurement basis to the quote before applying a price. Custom dimensions let you enter the rough-sawn or billed 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 an illustrative $0.85 per finished-volume 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 each group in a lumber list. Compare quotes only after confirming that both use the same dimensional basis. As a finished-volume illustration, 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?
The default mode uses actual milled dimensions, so the total reflects wood you can measure with a tape. Be aware that a supplier may tally 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,” choose Nominal tally from size to match that basis. 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, choose Custom dimensions 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.
Sources and assumptions
- Penn State Extension: Valuing Standing Timber — Defines the board-foot volume formula and gives a nominal 2 × 6 × 12 ft example of 12 board feet. Match the tally basis to your supplier.
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.