Calculator Tools
Board Foot Calculator
Calculate board feet for one or many lumber pieces. Quarters or inches input, waste allowance, linear feet, surface area, and project cost.
Thickness unit
Quarters is the standard rough lumber notation: 4/4 = 1 in, 5/4 = 1.25 in, 8/4 = 2 in.
Width unit
Length unit
Extra lumber to order to cover cutoffs, defects, and milling loss. 10% to 15% is typical for hardwoods.
Cut list
Add a row for each piece or each batch of identical pieces. Use Quantity for boards of the same size.
BF per piece
4
BF total (4 pcs)
16
Linear feet
24
BF per piece
15
BF total (4 pcs)
60
Linear feet
120
Dimensional lumber quick fill
Standard softwood (2x4, 2x6, etc) is sold by nominal size but board feet uses actual size. Tap a row to apply the actual thickness and width to the first piece in your cut list.
| Nominal | Actual (T x W) | BF per linear foot | BF in an 8 ft board | Action |
|---|---|---|---|---|
| 1 x 2 | 0.75 x 1.5 in | 0.0938 | 0.75 | |
| 1 x 4 | 0.75 x 3.5 in | 0.2188 | 1.75 | |
| 1 x 6 | 0.75 x 5.5 in | 0.3438 | 2.75 | |
| 1 x 8 | 0.75 x 7.25 in | 0.4531 | 3.625 | |
| 2 x 4 | 1.5 x 3.5 in | 0.4375 | 3.5 | |
| 2 x 6 | 1.5 x 5.5 in | 0.6875 | 5.5 | |
| 2 x 8 | 1.5 x 7.25 in | 0.9063 | 7.25 | |
| 2 x 10 | 1.5 x 9.25 in | 1.1563 | 9.25 | |
| 2 x 12 | 1.5 x 11.25 in | 1.4063 | 11.25 | |
| 4 x 4 | 3.5 x 3.5 in | 1.0208 | 8.1667 |
How the formula works
- Board foot: one board foot is 144 cubic inches of wood, the volume of a piece 1 in thick by 12 in wide by 12 in (1 ft) long. The formula in inches is (thickness x width x length) / 144.
- With length in feet: divide by 12 instead: BF = (T_in x W_in x L_ft) / 12. The two forms produce the same number.
- Quarters notation: 4/4 means four quarters of an inch (1.00 in), 5/4 is 1.25 in, 6/4 is 1.50 in, 8/4 is 2.00 in. The fraction always refers to quarters of an inch, not a literal division.
- Nominal vs actual: a 2x4 is sold as a 2x4 but actually measures 1.5 x 3.5 in once surfaced. Use the actual dimensions for board feet. The quick fill table above does this for you.
- Waste allowance: order 10 to 15% more than your finished cut list to cover cutoffs, defects, and milling. Cabinet and furniture builders often use 20 to 30% for rough lumber.
Common pitfalls
- Mixing units silently is the most common error. If thickness is in inches but length is in inches too, divide by 144, not 12. The unit toggles above lock the formula to the right divisor.
- S2S (surfaced two sides) and S4S boards are sold by nominal thickness. A 4/4 board you pick up at the lumberyard is usually 13/16 in thick after surfacing, but the price is still per BF at the nominal 1 in thickness.
- Plywood and sheet goods are not priced in board feet. They are sold by the sheet (4 ft x 8 ft) or by the square foot, not by volume.
- For odd lengths (a 7 ft 4 in board), convert the full length to feet first (7.333 ft) or to inches (88 in). Do not round the length until the very end of the calculation.
- Board feet measures volume, not price. Hardwood mills publish a per-BF price; multiply it by the BF total for the cost. Premiums for figure, grade, or width are added on top.
How to use
- Pick the units you want to type values in. Thickness can be Quarters (4/4 style), Inches, or Millimeters; width is Inches or Millimeters; length is Feet, Inches, or Millimeters.
- Fill in each cut list row with a Quantity, optional name, thickness, width, and length. Use the 4/4 through 16/4 chips to set thickness with one tap when using quarters input.
- Use Add piece to add another row for a different size, or remove rows you do not need. The totals panel updates as you type.
- For softwood dimensional lumber, tap a row in the quick fill table to push the actual milled dimensions (a 2x4 is 1.5 x 3.5 in) into the first cut list row.
- Set Waste allowance for cutoffs, defects, and milling loss. 10 to 15% is typical for hardwoods; 5 to 10% is enough for pre-surfaced softwood; 20 to 30% suits rough lumber projects.
- Turn on Estimate project cost and enter your supplier's price per board foot to see the project total with and without waste allowance, in any of the supported currencies.
- Use Copy summary for a printable plan, or Copy CSV to drop the cut list into a spreadsheet.
About this tool
Board Foot Calculator works out how much lumber you need in board feet (BF) for one piece or a multi-row cut list. A board foot is the standard unit of hardwood and rough lumber pricing: 144 cubic inches of wood, or a piece 1 in thick by 12 in wide by 1 ft long. The closed-form formula is (thickness in inches x width in inches x length in inches) divided by 144, or equivalently (T_in x W_in x L_ft) divided by 12 when length is in feet. The calculator accepts thickness in quarters notation (4/4, 5/4, 6/4, 8/4, 10/4, 12/4, 16/4), in plain decimal inches, or in millimeters, with one-click chips for the common quarter sizes. Width is in inches or millimeters; length is in feet, inches, or millimeters. Each cut list row carries quantity, an optional name, and dimensions, and the per-row card shows BF per piece, BF total, and linear feet. The totals card sums board feet, linear feet, and surface area (face square feet) across every valid row, with an explicit count of how many rows still need attention. A waste allowance slider (typically 10 to 15 percent for hardwoods) inflates the order quantity so you have enough material after cutoffs and defects, and an optional price-per-BF input multiplies the totals by your supplier's rate to produce a project cost in any of eight currencies. A reference table covers the most common dimensional softwood sizes (1x2 through 4x4) with the actual milled dimensions, the BF per linear foot, and a one-click action to push the actual values into the first row of your cut list (because nominal 2x4 lumber actually measures 1.5 x 3.5 in once surfaced and that is what board feet uses). Copy summary and Copy CSV buttons give you a portable record of any plan. Everything runs locally in your browser. No measurements are uploaded or stored.
Free to use. Works in your browser. No signup, no login.
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