Board Feet Calculator for Lumber
This calculator measures lumber the way sawmills and hardwood dealers sell it, in board feet. Enter a board's thickness and width in inches and its length in feet, and it multiplies those and divides by 12 to get the board feet in one piece. Set a quantity for the whole stack and an optional price per board foot to see total volume and project cost together.
How to calculate board feet
- Enter the board Thickness and Width in inches, using the 0.25 step for fractional sizes.
- Enter the board Length in feet.
- Set Quantity to the number of identical boards you are buying.
- Enter a Price per board foot to see a running cost, or leave it at zero.
- Read Board feet each, Total board feet and Total cost, then Copy estimate.
Examples
Ten 2x4 studs, 8 ft long, at $3.50 a board foot
Thickness 2 in, width 4 in, length 8 ft, quantity 10, $3.50/BF
5.3333 board feet each, 53.3333 total, $186.67
Ten 1x6 boards, 8 ft long, at $5.00 a board foot
Thickness 1 in, width 6 in, length 8 ft, quantity 10, $5.00/BF
4 board feet each, 40 total, $200.00
A single 8/4 hardwood slab, 8 in wide and 6 ft long
Thickness 2 in, width 8 in, length 6 ft, quantity 1, $8.00/BF
8 board feet each, 8 total, $64.00
Frequently asked questions
What exactly is a board foot?
A board foot is a volume unit equal to a piece 1 inch thick, 12 inches wide and 1 foot long, which is 144 cubic inches of wood. It measures volume, not surface area or linear length, which is why hardwood is commonly priced this way.
How is the board foot figure calculated?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2 by 4 that is 8 feet long is 2 times 4 times 8 divided by 12, which equals 5.3333 board feet. The total simply multiplies that by your quantity.
Should I enter nominal or actual lumber sizes?
Board feet are traditionally figured from nominal dimensions, so a 2x4 counts as a full 2 by 4 even though the surfaced board actually measures about 1.5 by 3.5 inches. Use the nominal numbers unless your supplier explicitly prices by actual dimensions.
What does a measurement like 4/4 or 8/4 mean?
Rough hardwood thickness is quoted in quarters of an inch. 4/4 is one inch, 5/4 is 1.25 inches and 8/4 is two inches. Enter the decimal inch value, for example 1.25 for 5/4, in the Thickness field.
Why is my 2x4 not a whole number of board feet?
Because 2 times 4 times 8 divided by 12 is 5.3333, not a round number. Many everyday sizes produce fractions and the tool keeps four decimals so nothing is lost. That is math, not a rounding bug.
How is the cost worked out?
Total cost is the total board feet multiplied by your price per board foot, rounded to the nearest cent. Leave the price at zero and the cost simply shows a dash while the board foot figures still calculate.
Does the estimate include waste or offcuts?
No. It returns the exact volume of the boards you specify. Woodworkers usually add 15 to 30 percent extra to cover defects, snipe, planer loss and mistakes, so bump up the quantity yourself to build in a cushion.
Can I mix different board sizes?
Not in one calculation, since it assumes identical boards. Run each size separately and add the totals, or use the per board figure to tally a cut list by hand.
Is anything I enter sent to a server?
No. The calculation runs entirely in your browser, so your dimensions and pricing stay on your device and the tool works offline once loaded.
Learn more
- Board feet vs linear feet: buying lumber without overpaying
The difference between board feet and linear feet, how nominal sizes affect the math, and how to budget a hardwood order with waste built in.
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