Board Foot Calculator
Convert any stack of lumber into board feet - enter the piece count, thickness, width and length to get total board feet, lineal feet and the cost at your price per board foot.
United States — national average · 2026 prices
Material only unless stated as installed. Excludes tax, permits and local labour. Verify with local suppliers — see how we calculate.
How this calculator works
Every figure above comes from the formula below, applied to the assumptions listed. Nothing is looked up from a hidden table — you can reproduce the result by hand.
Formula
board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12
total board feet = board feet per piece × number of pieces
cost = total board feet × price per board foot
Assumptions & limits
- Board feet are computed on NOMINAL dimensions by lumber-trade convention: a 2×4 counts as 2 by 4 even though it measures 1.5 × 3.5 inches.
- One board foot is 144 cubic inches of nominal lumber — a 1 in × 12 in × 12 in piece.
- Hardwood thickness is quoted in quarters: 4/4 = 1 in, 5/4 = 1.25 in, 8/4 = 2 in. Enter the quarter size as its decimal inch value.
- Construction lumber (2×4s, 2×6s) is usually priced per piece at the yard; board-foot pricing is primarily how hardwood is sold, graded under NHLA rules.
- The cost line uses your price exactly, with no added range — board-foot prices vary so much by species and grade that only your quoted price is meaningful.
Worked example
A lift of 24 pieces of 2×4 lumber, 8 ft long, priced at $4.00 per board foot
- Board feet per piece = 2 × 4 × 8 ÷ 12 = 5.33
- Total = 5.33 × 24 = 128 board feet
- Lineal feet = 24 × 8 = 192 ft
- Cost = 128 × $4.00 = $512
Result:128 board feet of lumber — $512 at $4.00 per board foot.
Built and maintained by Christoph Ballmer, Honeygoat GmbH
Method and constants last checked against the calculator code on August 25, 2026. Independent trade review is not yet in place for this calculator — see how we handle review.
Read the site-wide calculation methodology · estimate vs. quote and safety limits
What is a board foot?
A board foot is the volume unit lumber is measured and — for hardwood — priced in: the wood in a piece 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. It exists because lumber comes in every combination of thickness, width and length, and a volume unit is the only fair way to compare a wide short board against a narrow long one.
board feet = thickness (in) × width (in) × length (ft) ÷ 12
The convention that trips people up: board feet use nominal dimensions. A 2×4 counts as 2 by 4 in the formula even though the planed board in your hand measures 1.5 × 3.5 inches. That is how the trade has measured since lumber was sold rough-sawn, and every yard and every price list assumes it.
Board feet for common lumber sizes
| Size | Board feet per piece | Pieces per 100 bd ft |
|---|---|---|
| 1×6 × 8 ft | 4.0 | 25 |
| 2×4 × 8 ft | 5.33 | ≈ 19 |
| 2×6 × 10 ft | 10.0 | 10 |
| 2×8 × 12 ft | 16.0 | ≈ 6 |
| 2×12 × 16 ft | 32.0 | ≈ 3 |
The hardwood quarter system
Hardwood dealers quote thickness in quarters of an inch: 4/4 ("four quarter") is 1 inch, 5/4 is 1.25, 8/4 is 2 inches — always the rough-sawn thickness before surfacing. Enter the quarter size as its decimal value above. Price per board foot then swings far more with the NHLA grade (FAS, Select, No. 1 Common) than with the species itself, which is why two walnut boards can differ by a factor of three.
When you need this — and when you do not
Board feet matter when buying hardwood for furniture, trim or cabinetry, when comparing sawmill and dealer quotes, and when estimating a stack of framing lumber by volume. For a deck surface, the deck board calculator counts actual boards instead; for sheet goods, the plywood calculator works in 4×8 sheets. And if your yard prices 2×4s per stick — most do — the piece count from this calculator is the number to take to the counter, with the board footage as your cost cross-check.
Lumber prices vary by species, grade, region and week — the cost here uses exactly the price you enter, so get a current quote from your yard or sawmill before budgeting.
Frequently asked questions
How do I calculate board feet?
Multiply thickness (inches) x width (inches) x length (feet), then divide by 12. Use NOMINAL dimensions - a 2x4 counts as 2 by 4 even though it measures 1.5 x 3.5 - because that is the lumber-trade convention board feet are defined on. A 2x6 that is 10 ft long is 2 x 6 x 10 / 12 = 10 board feet. The calculator above does this per piece and totals the stack.
How many board feet is a 2x4x8?
A 2x4 that is 8 ft long is 2 x 4 x 8 / 12 = 5.33 board feet. A lift of 24 of them is 128 board feet. Note that construction lumber like 2x4s is usually priced per piece at the yard - board-foot pricing is mainly how hardwood is sold.
How many board feet are in a 1x12x12?
A 1x12 that is 12 ft long is 1 x 12 x 12 / 12 = 12 board feet - a handy one to remember, because a 1-inch board a foot wide carries exactly one board foot per foot of length.
What is the formula for a board foot?
Board feet = (thickness in inches x width in inches x length in feet) / 12. One board foot is the volume of a 1 in x 12 in x 12 in piece - 144 cubic inches of nominal lumber. Hardwood dealers quote thickness in quarters: 4/4 is 1 inch, 5/4 is 1.25, 8/4 is 2 inches.
Why is hardwood priced by the board foot?
Because hardwood comes in random widths and lengths, a volume unit is the only fair way to price it - two walnut boards of different shapes with the same board footage contain the same wood. Grading follows the National Hardwood Lumber Association rules, and the grade moves the price per board foot far more than the species alone.