Board Foot Calculator
Total board feet for a lumber list with 4/4 and 8/4 hardwood, nominal 2x lumber, waste and price per board foot, plus cubic metres and linear feet.
The interactive tool loads here when JavaScript runs.
About this toolWhat is the Board Foot Calculator?
Hardwood dealers and sawmills price lumber by the board foot, a volume of 144 cubic inches: one inch thick, twelve inches wide and one foot long. To compare a quote, plan a furniture build or check a mill tally you need the board feet of every line on your cutting list, plus an allowance for the knots, checks and offcuts you will cut away.
This calculator takes a list of boards, each with a quantity, thickness, width and length, and adds up the board feet. Thickness can be typed as hardwood quarters (4/4, 5/4, 8/4), as a fraction or decimal inch, or in millimetres. Lengths accept carpenter notation such as 8', 10' 6" or 96". Waste, price per board foot and a currency symbol turn the volume into a buying quantity and a cost.
Beside the list you get the volume in cubic metres and cubic feet, the total linear feet of boards, and a converter between linear feet and board feet for any cross section, which helps when a lumber yard prices trim or decking by the foot and a hardwood dealer prices by volume.
- Board list with quantity, quarter thickness, width and feet-inch lengths
- NHLA option to tally stock under 1 in as 1 in
- Waste allowance, cost per board foot and seven currency symbols
- Cubic metres, cubic feet and linear feet, plus a linear foot to board foot converter
- Metric input in millimetres and metres; copy and share link
How to use the Board Foot Calculator
- Choose imperial or metric. In imperial mode, type thickness as quarters (4/4, 8/4) or inches, width in inches and length in feet or feet and inches.
- Add one line for each board size and set the quantity. The quick-add buttons drop in common dimension sizes such as 2x4, 2x6 or 4x4.
- Enter a waste percentage. Rough hardwood often needs 15 to 30% for defects and offcuts; clear, dressed stock less.
- Enter the price per board foot to see the cost of the quantity you need to buy.
- Use the converter to turn linear feet of a given section into board feet, or the reverse, then copy the list or share a link.
Worked examples
Hardwood for a small table
Input
6 boards 4/4 x 6 in x 8 ft and 2 boards 8/4 x 8 in x 10 ft, 15% waste, $7.50 per BF
Output
50.67 BF net, 58.27 BF to buy, $437.00, 0.1196 m³
Each 4/4 board is 4 BF and each 8/4 board 13.33 BF. The waste allowance covers defects you will cut around, which is why the buying figure is higher than the net volume.
Ten 2x4 studs
Input
10 x 2 x 4 in x 8 ft
Output
53.33 BF, 80 linear feet
Dimension lumber is tallied on nominal sizes, so each stud is 5-1/3 BF even though its dressed section is 1-1/2 x 3-1/2 in.
Quarter-sawn oak quote check
Input
12 boards 5/4 x 7 in x 10 ft, 25% waste, $11 per BF
Output
87.5 BF net, 109.38 BF to buy, $1,203.13
A 5/4 board counts as 1.25 in thick, so each one is 1.25 x 7 x 10 / 12 = 7.29 BF.
Background and insight
The board foot formula is thickness in inches times width in inches times length in feet, divided by 12. A 2x4 eight feet long is 2 x 4 x 8 / 12 = 5-1/3 board feet, because softwood dimension lumber is tallied on its nominal size even though it is dressed to 1-1/2 x 3-1/2 in under the American Softwood Lumber Standard (NIST PS 20). Hardwood is different: it is sold rough, by quarter-inch thickness, so 4/4 stock is about one inch thick and 8/4 is about two. The National Hardwood Lumber Association rules also tally boards thinner than one inch as one inch, which the calculator offers as an option.
Because one inch is exactly 25.4 mm, one board foot is exactly 0.002359737 cubic metres and one cubic metre is 423.776 board feet. Timber sold by the cubic metre can therefore be compared directly with US pricing. The older Hoppus foot used for round logs in Britain and parts of Asia is a different measure (about 1.27 true cubic feet) and is not used here.
Common use cases
Buying rough hardwood
Turn a project cut list into board feet with a defect allowance before visiting a hardwood dealer.
Checking a sawmill tally
Re-add a mill ticket line by line to confirm the volume you are paying for.
Comparing by-the-foot and by-volume prices
Convert a per-linear-foot price for a given section into a price per board foot or per cubic metre.
Estimating sawlog yield
Total the boards you expect from a log or a stack of slabs to compare against a log scale.
Tips and limitations
- Hardwood widths are random. Measure each board, or average a bundle, rather than assuming a nominal width.
- Rough 4/4 planes down to about 13/16 in. Buy thicker stock when the finished part has to be a full inch.
- Some dealers round widths to the nearest inch and lengths down to the whole foot. Ask how they tally before comparing quotes.
- Plywood and sheet goods are sold by the sheet, not by the board foot.
- Kiln-dried and air-dried lumber shrink differently; buy a little extra for wood that still has to acclimatise.
Frequently asked questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet and divide by 12. A board 1 in thick, 6 in wide and 8 ft long is 1 x 6 x 8 / 12 = 4 board feet. If the length is in inches, divide by 144 instead.
How many board feet are in a 2x4x8?
5.33 board feet. Softwood is tallied on nominal size, so 2 x 4 x 8 / 12 = 5-1/3, even though the stud actually measures 1-1/2 x 3-1/2 in.
What does 4/4 or 8/4 mean for lumber?
It is the rough thickness of hardwood in quarters of an inch. 4/4 (four quarter) is about 1 in, 5/4 is 1-1/4 in, 6/4 is 1-1/2 in and 8/4 is 2 in. Board feet are tallied on that rough thickness, before planing.
How many board feet are in a cubic metre?
423.776. One board foot is 144 cubic inches, which is exactly 0.002359737 cubic metres because an inch is exactly 25.4 mm.
How do I convert linear feet to board feet?
Multiply linear feet by thickness and width in inches and divide by 12. Twelve linear feet of 2x6 is 12 x 2 x 6 / 12 = 12 board feet. The converter in the calculator does this in both directions.
How much extra lumber should I buy for waste?
For rough hardwood, 15 to 30% is common because you cut around knots, splits and end checks. For clear, surfaced stock or dimension lumber for framing, 5 to 10% is usually enough.
Is there an in-depth guide to the Board Foot Calculator?
Yes. “How to Calculate Board Feet: Hardwood, Dimension Lumber and Metric” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
Related Tools You May Like
Free, in-browser tools that pair well with this one.