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Lumber board feet calculator
Put the thickness, width, length, quantity and price in: a 2x6 board 8 ft long is 8.00 board feet, $9.60 at $1.20 per board foot.
★ CONSTRUCTION · LUMBER · BOARD FEET
Lumber Board Feet Chart: Board Feet by Size & Length
On the defaults — a 2x6 board, 8 ft long — the board feet are 8.00, the cost at $1.20 per board foot is $9.60, and 12.50 such boards make 100 board feet. This one is the BOARD-FEET VOLUME chart — thickness times width times length in feet divided by 12, with the size-by-length table, the cost extension, and the reverses (length for a target volume, boards for a target total) — the board-foot-calculator page is the single-board CALCULATOR — one board at a time, no size table — not the chart; the lumber-size-chart page is the NOMINAL-VS-ACTUAL dimensions chart — what a 2x4 really measures — not a volume figure; the paint-coverage-chart and tile-coverage-chart pages are AREA coverage charts — square feet per gallon or per box — not board-feet volume, which counts thickness too.
What does 8.00 board feet mean?
It means the board holds 8.00 units of lumber volume, where one board foot is a piece 1 inch thick, 12 inches wide and 12 inches long — 144 cubic inches, or one-twelfth of a cubic foot. A 2x6 board 8 ft long is 2 × 6 × 8 ÷ 12, which is 8.00 board feet, and at $1.20 per board foot it costs $9.60. Because board feet measure volume, a short thick board and a long thin board can hold the same board feet: a 2x4 at 12 ft and a 1x12 at 8 ft are both 8.00 board feet. That is the point of the unit — it prices wood by how much wood there is, not by how long it is.
Board feet by size and length
Board feet per board and boards per 100 board feet for the common sizes, with the cost per board at $1.20 per board foot. The table uses nominal sizes, as lumberyards price them; a 2x4 is not actually 2 inches by 4 inches once planed, and the actual volume of the wood in your hand is smaller — the board-foot figure is the trade figure, not a tape-measure volume.
| Size | Length | Board feet per board | Boards per 100 board feet | Cost per board at $1.20 |
|---|---|---|---|---|
| 2x4 | 8 ft | 5.33 | 18.75 | $6.40 |
| 2x4 | 10 ft | 6.67 | 15.00 | $8.00 |
| 2x4 | 12 ft | 8.00 | 12.50 | $9.60 |
| 2x6 | 8 ft | 8.00 | 12.50 | $9.60 |
| 2x6 | 10 ft | 10.00 | 10.00 | $12.00 |
| 2x6 | 12 ft | 12.00 | 8.33 | $14.40 |
| 2x8 | 8 ft | 10.67 | 9.38 | $12.80 |
| 2x8 | 10 ft | 13.33 | 7.50 | $16.00 |
| 2x8 | 12 ft | 16.00 | 6.25 | $19.20 |
| 4x4 | 8 ft | 10.67 | 9.38 | $12.80 |
| 4x4 | 10 ft | 13.33 | 7.50 | $16.00 |
| 4x4 | 12 ft | 16.00 | 6.25 | $19.20 |
| 1x6 | 8 ft | 4.00 | 25.00 | $4.80 |
| 1x6 | 10 ft | 5.00 | 20.00 | $6.00 |
| 1x6 | 12 ft | 6.00 | 16.67 | $7.20 |
| 1x8 | 8 ft | 5.33 | 18.75 | $6.40 |
| 1x8 | 10 ft | 6.67 | 15.00 | $8.00 |
| 1x8 | 12 ft | 8.00 | 12.50 | $9.60 |
Boards per 100 board feet is the exact figure 1200 divided by thickness times width times length — for a 2x8 at 8 ft that is 1200 ÷ 128, which is 9.375, shown as 9.38. Ordering by it directly would leave you short, because boards come whole: 100 board feet from 8.00-board-foot boards is 13 boards (104.00 board feet), not 12.5. Always round the board count up, then add waste for cuts and defects.
Three things to check before you trust the number
Length goes in feet, thickness and width in inches. The divisor 12 is the unit conversion: length in feet times 12 is length in inches, and thickness times width times length in inches divided by 144 is the board feet. If you type the length in inches by mistake, the answer comes out 12 times too big — a 2x6 at 96 inches typed as 96 ft would read 96.00 board feet instead of 8.00. If all three dimensions are in inches, divide by 144 instead.
Nominal is not actual. Lumberyards price by nominal size: a 2x6 counts as 2 by 6 inches even though the planed board you take home is about 1.5 by 5.5 inches. The board-foot figure on this page is the trade figure, and the price per board foot is quoted on the same basis, so the cost is right even though the physical volume is smaller. If you want the true volume of the wood in your hand, measure the actual board and type those numbers in.
Round boards up, then add waste. Boards per 100 board feet is a rate, not an order: 12.50 boards per 100 board feet means 13 boards to cover 100 board feet, giving 104.00 board feet, and then cuts, defects and mistakes take their share on top. Rough hardwood in particular hides knots, checks and wane, and the usual advice is 15% extra for it. The calculator gives the exact volume; the order quantity is your call.
Worked example
On the defaults: a 2x6 board, 8 ft long, 1 board, $1.20 per board foot.
- The product: 2 × 6 × 8 is 96.
- The board feet: 96 ÷ 12 is 8.00.
- The total: 8.00 × 1 is 8.00 board feet.
- The cost: 8.00 × $1.20 is $9.60.
- The rate: 1200 ÷ (2 × 6 × 8) is 12.50 boards per 100 board feet.
And the other way: the length needed for 10.00 board feet from a 2x6 is 10 ft, and the boards needed for 100 board feet from 8.00-board-foot boards are 13 boards (12 boards give only 96.00 board feet, so 12 is short; 14 give 112.00).
Every branch, checked
- A 2x4, 12 ft long: A 2x4, 12 ft long: 8.00 board feet per board; 8.00 board feet total for 1 board(s); $9.60 at $9.60 a board.
- A 4x6, 10 ft long: A 4x6, 10 ft long: 20.00 board feet per board; 20.00 board feet total for 1 board(s); $24.00 at $24.00 a board.
- A 1x12, 8 ft long: A 1x12, 8 ft long: 8.00 board feet per board; 8.00 board feet total for 1 board(s); $9.60 at $9.60 a board.
- A 2x12, 16 ft long: A 2x12, 16 ft long: 32.00 board feet per board; 32.00 board feet total for 1 board(s); $38.40 at $38.40 a board.
- A 6x6 post, 8 ft long: A 6x6 post, 8 ft long: 24.00 board feet per board; 24.00 board feet total for 1 board(s); $28.80 at $28.80 a board.
- Ten 2x6, 8 ft boards: Ten 2x6, 8 ft boards: 8.00 board feet per board; 80.00 board feet total for 10 board(s); $96.00 at $9.60 a board.
The reverses, worked backwards
- Length needed for 10.00 board feet from a 2x6: 10 ft — at 10 ft the figures are 10.00 board feet per board; 10.00 board feet total for 1 board(s); $0.00 at $0.00 a board.; at the lower neighbor the figures are 9.00 board feet per board; 9.00 board feet total for 1 board(s); $0.00 at $0.00 a board.; at the upper neighbor the figures are 11.00 board feet per board; 11.00 board feet total for 1 board(s); $0.00 at $0.00 a board. — verdict: STEP.
- Boards needed for 100 board feet from 8.00-board-foot boards: 13 boards — at 13 boards the figures are 8.00 board feet per board; 104.00 board feet total for 13 board(s); $0.00 at $0.00 a board.; at the lower neighbor the figures are 8.00 board feet per board; 96.00 board feet total for 12 board(s); $0.00 at $0.00 a board.; at the upper neighbor the figures are 8.00 board feet per board; 112.00 board feet total for 14 board(s); $0.00 at $0.00 a board. — verdict: STEP.
What the defaults assume
The defaults are a 2x6 board, 8 ft long, 1 board, at $1.20 per board foot. The model is one division: board feet per board is thickness in inches times width in inches times length in feet divided by 12, the total multiplies by the quantity, and the costs multiply by the price per board foot. Boards per 100 board feet is computed exactly as 1200 divided by thickness times width times length, never from the rounded per-board figure — that is why a 2x8 at 8 ft shows 9.38 boards per 100 board feet (exact 9.375) rather than 9.37. The length reverse is checked at 1 ft either side, because a 1-ft change on a 2x6 is exactly 1.00 board foot; the boards reverse is checked at 1 board either side, because one board is 8.00 board feet and shows the short-or-covered step cleanly. The model uses nominal sizes, assumes straight boards with no waste allowance, and does not price by species, grade, or delivery — those are quoted per board foot by the yard.
Formula check against independent references
The 12-divisor formula was verified against independent board-foot references before this page shipped: board feet equal thickness in inches times width in inches times length in feet divided by 12, and one board foot is 144 cubic inches. The worked examples in those references agree with this page — a 2x4 at 8 ft is 5.33 board feet, a 2x6 at 10 ft is 10 board feet, and a 6x6 post at 12 ft is 36 board feet. The formula here is the same arithmetic in our own words and our own table; no reference text is copied.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Board feet per board | thickness (in) × width (in) × length (ft) ÷ 12 | 8.00 — 2 × 6 × 8 ÷ 12. |
| Total board feet | board feet per board × quantity | 8.00 — 8.00 × 1. |
| Cost per board | board feet per board × price per board foot | $9.60 — 8.00 × $1.20. |
| Total cost | total board feet × price per board foot | $9.60 — 8.00 × $1.20. |
| Boards per 100 board feet | 1200 ÷ (thickness × width × length) | 12.50 — 1200 ÷ (2 × 6 × 8). |
| Cubic feet per board | board feet per board ÷ 12 | 0.67 — 8.00 ÷ 12. |
| Reverse: Length needed for 10.00 board feet from a 2x6 | step | 10 ft: 10.00 board feet per board; 10.00 board feet total for 1 board(s); $0.00 at $0.00 a board. |
| Reverse: Boards needed for 100 board feet from 8.00-board-foot boards | step | 13 boards: 8.00 board feet per board; 104.00 board feet total for 13 board(s); $0.00 at $0.00 a board. |
| A 2x4, 12 ft long | same model | 8.00 board feet per board; 8.00 board feet total for 1 board(s); $9.60 at $9.60 a board. |
| A 4x6, 10 ft long | same model | 20.00 board feet per board; 20.00 board feet total for 1 board(s); $24.00 at $24.00 a board. |
| A 1x12, 8 ft long | same model | 8.00 board feet per board; 8.00 board feet total for 1 board(s); $9.60 at $9.60 a board. |
| A 2x12, 16 ft long | same model | 32.00 board feet per board; 32.00 board feet total for 1 board(s); $38.40 at $38.40 a board. |
| A 6x6 post, 8 ft long | same model | 24.00 board feet per board; 24.00 board feet total for 1 board(s); $28.80 at $28.80 a board. |
| Ten 2x6, 8 ft boards | same model | 8.00 board feet per board; 80.00 board feet total for 10 board(s); $96.00 at $9.60 a board. |
| Length 0 ft | same model | 0.00 board feet per board; 0.00 board feet total for 1 board(s); $0.00 at $0.00 a board. |
| Thickness 0 in | same model | Thickness and width — more than 0. |
| Price $0 per board foot | same model | 8.00 board feet per board; 8.00 board feet total for 1 board(s); $0.00 at $0.00 a board. |
| One hundred 2x6, 8 ft boards | same model | 8.00 board feet per board; 800.00 board feet total for 100 board(s); $960.00 at $9.60 a board. |
Who uses this
- A woodworker pricing a project — a 2x6 at 8 ft is 8.00 board feet and $9.60 at $1.20: the material cost before a single cut.
- A contractor ordering lumber — 100 board feet from 8.00-board-foot boards is 13 boards, not 12.5: the order quantity, rounded up, with waste on top.
- A DIYer checking a lumberyard quote — ten 2x6 boards at 8 ft are 80.00 board feet and $96.00 at $1.20: the quote checked against the volume.
- A student learning trade units — one worked example from dimensions to board feet to cost, and the table that shows why volume, not length, is the unit.
Accuracy & limitations
Figures are the model's own arithmetic on the numbers you type, computed from unrounded values: board feet per board is thickness times width times length in feet divided by 12, the total multiplies by the quantity, costs multiply by the price per board foot, and boards per 100 board feet is 1200 divided by thickness times width times length. The displayed figures are rounded to 2dp. The main limitation is nominal versus actual size: lumberyards price by nominal size, so the board-foot figure is the trade figure, and the actual planed board holds less wood. The model assumes straight, defect-free boards and no waste allowance, and it does not price by species, grade, finish, or delivery. This page is a calculation tool, not a lumber-grading or purchasing service.
Cite this calculator
A 2x6 board 8 ft long is 8.00 board feet; at $1.20 per board foot it costs $9.60, and 12.50 such boards make 100 board feet. Source: Bright Side Kit, brightoolbox.com.
Frequently asked questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2x6 board 8 ft long is 2 × 6 × 8 ÷ 12, which is 8.00 board feet.
How many board feet is a 2x4 at 8 ft?
5.33 board feet. 2 × 4 × 8 ÷ 12 is 5.33, and 18.75 such boards make 100 board feet.
How many 2x6 boards at 8 ft make 100 board feet?
13 boards, giving 104.00 board feet. 12 boards give only 96.00 board feet, so 12 is short — always round the board count up.
What length of 2x6 gives 10.00 board feet?
10 ft. At 9 ft a 2x6 is 9.00 board feet; at 11 ft it is 11.00 board feet.
Why divide by 12 and not 144?
Because the length is already in feet. Length in feet times 12 is length in inches, and thickness times width times length in inches divided by 144 is the same figure. If all three dimensions are in inches, divide by 144.
Is a board foot the same as a square foot?
No — board feet measure volume, square feet measure area. Thickness is part of a board foot and absent from a square foot, so a thick board and a thin board of the same area hold different board feet.
Do I use nominal or actual dimensions?
Nominal, as lumberyards price them. A 2x6 counts as 2 by 6 inches for pricing even though the planed board is smaller. Type actual measurements only if you want the true volume of the wood in your hand.
How much does a 2x6 board at 8 ft cost at $1.20 per board foot?
$9.60. 8.00 board feet times $1.20, and ten such boards are 80.00 board feet for $96.00.