Materials & quantities
Board foot & lumber calculator
Total board feet, cubic metres and linear feet for a lumber list, on nominal or actual sizes, with waste and cost.
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What a board foot calculator does
A board foot calculator converts a list of lumber into board feet, the volume unit North American lumberyards and sawmills price by. One board foot is a piece 1 in thick, 12 in wide and 12 in long, or 144 cubic inches. Enter each piece's count, thickness, width and length, and the calculator returns the board feet per piece and per row, the total with your waste allowance, the linear footage and an optional cost.
The formula is board feet = thickness (in) × width (in) × length (ft) ÷ 12. A 2 × 6 that is 12 ft long is 2 × 6 × 12 ÷ 12 = 12 board feet, so ten of them are 120 board feet. Softwood dimension lumber is priced on its nominal size, even though a dry 2 × 6 actually measures 1½ × 5½ in, so the calculator defaults to the nominal basis in imperial and also reports the dressed volume of wood you receive.
Switch to Metric and the same list is measured in cubic metres on the sizes you enter, which is how metric timber is sold. Rough-sawn hardwood is measured by its rough thickness in quarters (4/4, 8/4), so enter those on the as-entered basis. The tool measures volume only: it does not choose grades, optimise cutting or size structural members.
How to use the board foot & lumber calculator
- Choose Imperial or Metric. Imperial is the default, and your choice carries across the free tools.
- Set the Size basis. Nominal US softwood (PS 20 dressed sizes) counts a 2 × 6 as 2 × 6 in and adds the dressed volume; As entered (actual or rough) uses your dimensions exactly, for metric sections and rough hardwood.
- In the piece table, enter a name, Count, Thickness, Width and Length for each size and length you need. Use Add piece for every line of your lumber list.
- Set a Waste allowance percentage and, if you want a cost, the Optional price per board foot (per m³ in metric).
- Read the pieces, total linear length, lumber volume before and with waste, the dressed volume on the nominal basis, the cost and the per-row table. Download the PDF or CSV, or use Save inputs to reopen the list later.
Worked example
Imperial: Ten 2 × 6 boards 12 ft long are 120 board feet on nominal sizes (82.5 board feet of dressed 1½ × 5½ in wood) and 120 linear feet; a 10% allowance gives 132 board feet.
Metric: Ten 45 × 90 mm studs 3 m long are 0.1215 m³ of timber and 30 m of stock; a 10% allowance gives 0.1337 m³.
How to calculate board feet
Multiply the thickness in inches by the width in inches and the length in feet, then divide by 12. If all three dimensions are in inches, divide by 144 instead. For a whole order, multiply each piece by its count and add the rows.
Board feet per linear foot is thickness × width ÷ 12, which is the quickest way to price dimension lumber sold by the foot: a 2 × 6 is exactly 1 board foot per linear foot, a 2 × 4 is two-thirds, and a 2 × 12 is 2. The table uses nominal sizes, as lumberyards do.
| Nominal size | Per linear ft | 8 ft piece | 10 ft piece | 12 ft piece | 16 ft piece |
|---|---|---|---|---|---|
| 1 × 4 | 0.333 | 2.67 | 3.33 | 4.00 | 5.33 |
| 1 × 6 | 0.500 | 4.00 | 5.00 | 6.00 | 8.00 |
| 1 × 12 | 1.000 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 4 | 0.667 | 5.33 | 6.67 | 8.00 | 10.67 |
| 2 × 6 | 1.000 | 8.00 | 10.00 | 12.00 | 16.00 |
| 2 × 8 | 1.333 | 10.67 | 13.33 | 16.00 | 21.33 |
| 2 × 10 | 1.667 | 13.33 | 16.67 | 20.00 | 26.67 |
| 2 × 12 | 2.000 | 16.00 | 20.00 | 24.00 | 32.00 |
| 4 × 4 | 1.333 | 10.67 | 13.33 | 16.00 | 21.33 |
| 6 × 6 | 3.000 | 24.00 | 30.00 | 36.00 | 48.00 |
Nominal vs actual lumber sizes
Softwood lumber is named by its rough size before drying and planing. The American Softwood Lumber Standard (PS 20) sets the dressed sizes: boards under 2 in lose ¼ in, dimension lumber from 2 to 7 in loses ½ in, and widths of 8 in and more lose ¾ in. Timbers 5 in and thicker are surfaced green and are about ½ in under on each dimension.
Board footage for pricing stays on the nominal size, so the wood you receive is only about two-thirds to four-fifths of the nominal board feet. The calculator's dressed volume is the figure to use for weight, shrinkage or embodied-carbon estimates.
| Nominal | Dressed size | Nominal board ft per ft | Dressed board ft per ft | Dressed share |
|---|---|---|---|---|
| 1 × 4 | ¾ × 3½ in | 0.333 | 0.219 | 66% |
| 1 × 6 | ¾ × 5½ in | 0.500 | 0.344 | 69% |
| 2 × 4 | 1½ × 3½ in | 0.667 | 0.438 | 66% |
| 2 × 6 | 1½ × 5½ in | 1.000 | 0.688 | 69% |
| 2 × 8 | 1½ × 7¼ in | 1.333 | 0.906 | 68% |
| 2 × 10 | 1½ × 9¼ in | 1.667 | 1.156 | 69% |
| 2 × 12 | 1½ × 11¼ in | 2.000 | 1.406 | 70% |
| 4 × 4 | 3½ × 3½ in | 1.333 | 1.021 | 77% |
| 6 × 6 | 5½ × 5½ in | 3.000 | 2.521 | 84% |
Board feet, cubic feet and cubic metres
A board foot is 144 in³, so 12 board feet make one cubic foot. In metric terms one board foot is 0.00236 m³, and one cubic metre is about 423.8 board feet. Mills and log scales often quote thousands of board feet (MBF); 1 MBF is about 2.36 m³.
Metric timber is sold by the cubic metre or by the linear metre of a stated actual section, such as 90 × 45 mm. Switching the calculator to Metric reports cubic metres on the sizes you type, and the price field becomes a price per m³.
| Quantity | Equals |
|---|---|
| 1 board foot | 144 in³ = 0.0833 ft³ = 0.00236 m³ |
| 12 board feet | 1 ft³ |
| 1,000 board feet (1 MBF) | 83.3 ft³ = 2.36 m³ |
| 1 m³ | 423.8 board feet = 35.3 ft³ |
| 90 × 45 mm, 1 m long | 0.00405 m³ = 1.72 board feet |
Hardwood thickness in quarters
Hardwood is sold rough by the board foot, with thickness stated in quarter inches: 4/4 ("four quarter") is 1 in rough, 8/4 is 2 in. Board feet are measured on the rough thickness and the actual width and length of each board, so choose As entered (actual or rough) and type the rough thickness.
Surfacing removes material, and the surfaced (S2S) thickness is what reaches the project. The figures below are typical surfaced thicknesses; check the mill's own specification.
| Quarter | Rough thickness | Typical S2S thickness | Board ft per ft at 6 in wide |
|---|---|---|---|
| 4/4 | 1 in | 13/16 in | 0.500 |
| 5/4 | 1¼ in | 1-1/16 in | 0.625 |
| 6/4 | 1½ in | 1-5/16 in | 0.750 |
| 8/4 | 2 in | 1¾ in | 1.000 |
| 12/4 | 3 in | 2¾ in | 1.500 |
Worked example: a deck framing lumber list
A deck frame needs thirteen 2 × 8 joists 12 ft long, two 2 × 8 rim joists 16 ft long, three 2 × 10 beam plies 16 ft long and four 6 × 6 posts 10 ft long. On nominal sizes that is 208 + 42.67 + 80 + 120 = 450.67 board feet across 22 pieces and 276 linear feet. A 10% allowance makes it 495.73 board feet.
The dressed volume is 326.71 board feet, about 72% of the nominal figure, because the joists and beam plies are 1½ in thick and the posts 5½ in square. In metric terms the order is about 1.06 m³ nominal.
| Piece | Count | Size | Length | Board feet |
|---|---|---|---|---|
| Joists | 13 | 2 × 8 | 12 ft | 208.00 |
| Rim joists | 2 | 2 × 8 | 16 ft | 42.67 |
| Beam plies | 3 | 2 × 10 | 16 ft | 80.00 |
| Posts | 4 | 6 × 6 | 10 ft | 120.00 |
| Total | 22 | 276 ft | 450.67 |
Who it is for and when to use it
Pricing a lumber order
Turn a cut list or framing take-off into board feet and multiply by the yard's price per board foot, or compare it with a price per piece.
Buying hardwood for furniture and millwork
Enter rough 4/4 or 8/4 boards on the as-entered basis to see the board feet a hardwood dealer will charge for, with an allowance for defects and milling.
Converting between imperial and metric timber
Switch units to compare a US lumber list in board feet with a metric quote in cubic metres.
Estimating wood volume for carbon or weight
Use the dressed volume rather than nominal board feet for embodied-carbon or weight estimates, then carry it into the embodied-carbon comparison.
Method, formulas & assumptions
Board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12; metric volume = thickness × width × length in m³ (1 board foot = 144 in³ = 0.00236 m³). Row totals multiply by the piece count, and the waste allowance is applied to the total volume. On the nominal basis, volume uses the named size and a second figure uses PS 20 dry dressed sizes (boards less ¼ in, 2–7 in less ½ in, 8 in and wider less ¾ in; timbers less ½ in). Cost = volume with waste × your price per board foot or per m³.
Imperial inputs are converted with exact factors (1 ft = 0.3048 m, 1 lb = 0.45359237 kg, 1 US gal = 3.785411784 L) before the calculation runs in SI, then results are converted back.
Common mistakes to avoid
- Mixing feet and inches. The formula takes thickness and width in inches but length in feet; with all three in inches, divide by 144.
- Pricing on actual sizes when the yard prices on nominal sizes. A 2 × 6 is sold as 1 board foot per foot, not 0.69.
- Using nominal board feet for weight or carbon. The wood you receive is roughly two-thirds to four-fifths of the nominal volume.
- Entering surfaced hardwood thickness. Hardwood is measured on its rough thickness: a 4/4 board is 1 in, even when it arrives at 13/16 in.
- Leaving out the waste allowance. Defects, end trimming and cutting losses typically need 10 to 15% for framing and more for appearance-grade hardwood.
Scope & limits
Board measure only. Prices, grades, species and moisture content are yours to confirm; enter rough hardwood (4/4, 8/4) on the as-entered basis. Pieces are not optimised into stock lengths, and nothing here sizes structure.
Frequently asked questions
How do you calculate a board foot?
Multiply thickness in inches by width in inches by length in feet and divide by 12. A 2 × 6 that is 12 ft long is 2 × 6 × 12 ÷ 12 = 12 board feet.
How many board feet are in a 2x4x8?
A 2 × 4 that is 8 ft long is 2 × 4 × 8 ÷ 12 = 5.33 board feet on its nominal size. Its dressed 1½ × 3½ in section holds 3.5 board feet of actual wood.
Do you use nominal or actual size for board feet?
Softwood dimension lumber is priced on nominal sizes, so a 2 × 6 counts as 2 × 6 in. Rough hardwood uses its rough thickness and actual width. The calculator offers both bases and reports the dressed volume on the nominal basis.
How many board feet are in a cubic foot?
Twelve. A cubic foot is 1,728 in³ and a board foot is 144 in³.
How many board feet are in a cubic metre?
About 423.8. One board foot is 0.00236 m³, so 1,000 board feet is about 2.36 m³.
What does 4/4 or 8/4 mean for hardwood?
It is the rough thickness in quarter inches: 4/4 is 1 in and 8/4 is 2 in. Board feet are calculated on that rough thickness.
How much waste should I add to a lumber order?
About 10% is common for framing, more for appearance-grade boards and hardwood with defects to cut around. The calculator applies whatever percentage you enter to the total volume.
Does the calculator work in metric?
Yes. Switch to Metric to enter millimetres and metres and get cubic metres. Ten 90 × 45 mm pieces 3 m long are 0.1215 m³.
Do I need an account to download the result?
No. All calculations, local file processing and exports on this page are free, without an account.
Where are my inputs stored?
The tool keeps inputs in this browser tab. It does not upload them or create a cloud copy. Save or download anything you want to keep before leaving the page. Standard site analytics may operate independently of the tool.
Can I work in metric instead of imperial?
Yes. Use the Imperial / Metric switch above the inputs. Imperial (feet, inches, pounds, gallons) is the default; switching converts every dimensional field and result, and your choice is remembered across the free tools in this browser.
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