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Lumber calculator
Put your board size, length and count in: a 2 in by 6 in board, 8 ft long, is 8 board feet — 20 boards total 160 board feet.
★ CONSTRUCTION · LUMBER · BOARD FEET
Lumber Calculator: 160 Board Feet for 20 Boards of 2×6
On the defaults — 2 in by 6 in boards, 8 ft long, 20 boards — you need 160 board feet of lumber. This is the lumber tool: enter the board name size, the length and the count, and get the volume the merchant prices.
What does lumber needed 160 board feet mean?
It means twenty boards, each 2 in thick, 6 in wide and 8 ft long, contain 160 board feet of lumber. A board foot is a volume: a board 1 in thick, 12 in wide and 1 ft long, or 144 cubic inches, and lumber is priced by it. One board here is 2 times 6 times 8 divided by 12, or 8 board feet — the 12 in the division converts the width from inches to feet. Twenty boards at 8 board feet each total 160, and that is the number the merchant prices, not the board count alone.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Board feet per board | thickness × width × length ÷ 12 | 8 board feet — 2 × 6 × 8 ÷ 12. |
| Total board feet | board feet per board × boards | 160 board feet — 8 × 20. |
Three things to check before you trust the number
First, check the board name means nominal size: a 2×6 board is sold as 2 in by 6 in but measures nearer 1.5 in by 5.5 in dressed, while board feet are figured on the nominal size — so use the name size here, not the tape size. Second, check the length is in feet and the cross-section in inches: mixing units is the classic board-foot error, and the division by 12 is what converts inches to feet. Third, remember the total is lumber volume only — it does not include offcuts, and a cut list with many short pieces wastes more than a list of full-length boards.
Worked example
2 in thick, 6 in wide, 8 ft long, 20 boards. Board feet per board: 2 × 6 × 8 ÷ 12 = 8. Total: 8 × 20 = 160 board feet. In practice that means ordering 160 board feet, and expecting the merchant to price by that volume rather than by the board count. If the same boards were 10 ft long instead, each would be 10 board feet and the total 200 board feet, but the board count would be identical.
Every branch, checked
With 4 in thick boards instead of 2 in, each board is 16 board feet and the total is 320 board feet. With 12 in wide boards, each board is again 16 board feet and the total 320 board feet. With 10 ft long boards, each board is 10 board feet and the total 200 board feet. With 10 boards instead of 20, each board stays 8 board feet and the total falls to 80 board feet. Thickness, width, length and count each move the total on their own, so a wrong board name is as costly as a wrong count.
The reverses, worked backwards
The thickness behind 160 board feet is 2 in: at 1 in the need is 80 board feet (4 board feet per board, 20 boards); at 4 in it is 320 board feet (16 board feet per board, 20 boards). The width behind 160 board feet is 6 in: at 3 in the need is 80 board feet (4 board feet per board, 20 boards); at 12 in it is 320 board feet (16 board feet per board, 20 boards). The length behind 160 board feet is 8 ft: at 4 ft the need is 80 board feet (4 board feet per board, 20 boards); at 16 ft it is 320 board feet (16 board feet per board, 20 boards). Each reverse moves one input and holds the rest, so the step is exactly one dimension or one count change.
What the defaults assume
The defaults assume twenty 2 in by 6 in boards, 8 ft long, figured at nominal size. They do not assume dressed dimensions, offcuts, a mix of board sizes, or delivery — a cut list with several sizes should be run once per size and the board feet added, and the dressed size of a board is smaller than its name size.
Who uses this
- A homeowner buying lumber for a deck frame: the 160-board-foot total is the number the merchant prices, not the board count.
- A DIY builder pricing a project: the same maths per board size gives the lumber line on the project budget.
- A contractor quoting a frame: thickness, width, length, count — the quote follows the same two steps, and the per-board figure shows the client why.
- A woodworker comparing board sizes: board feet put a 2×6 and a 1×12 on the same footing, volume against volume.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the board size convention. Board feet are figured on nominal size, so a dressed 2×6 measures smaller than the 2 in by 6 in entered here — that is the trade convention, not an error. Real cut lists waste offcuts, and a list of short pieces needs more boards than the finished lengths suggest. Treat 160 board feet as the lumber volume for twenty full-length nominal 2×6 boards, and add boards for offcuts before ordering.
Cite this calculator
Bright Side Kit, “Lumber Calculator: 160 Board Feet for 20 Boards of 2×6”, https://brightoolbox.com/lumber-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (2 in × 6 in boards, 8 ft long, 20 boards) so the 160-board-foot result can be checked.
Frequently asked questions
How many board feet are in a 2×6 board 8 ft long?
8 board feet. Thickness times width times length, divided by 12: 2 × 6 × 8 ÷ 12 = 8. Twenty such boards total 160 board feet.
What is a board foot?
A volume: 144 cubic inches, the volume of a board 1 in thick, 12 in wide and 1 ft long. Lumber is priced by the board foot, so the total here, not the board count, is what the merchant charges on.
Why divide by 12 in the board-foot formula?
Because thickness and width are in inches and length is in feet. Dividing by 12 converts the cross-section to square feet, and square feet times feet gives cubic feet — scaled to board feet.
Is a 2×6 really 2 inches by 6 inches?
By name, yes; by tape, no. A dressed 2×6 measures nearer 1.5 in by 5.5 in, but board feet are figured on the nominal name size, which is what this calculator uses.
How do I price lumber once I know the board feet?
Multiply board feet by the price per board foot for that species and grade. The deck board calculator counts decking boards for the same kind of project, board by board.
What if my cut list has several board sizes?
Run each size separately and add the board feet. A mixed list figured as one size under-orders the larger boards and over-orders the smaller ones.