Measure lumber the way sawmills and lumberyards do. Enter the number of boards and each board's thickness, width, and length, and the calculator finds the board feet per piece, the total board feet, and — if you add a price — the total cost. One board foot is a piece 1 inch thick, 12 inches wide, and 1 foot long.
The board foot calculator works out how much lumber you have or need using the unit the timber trade runs on: the board foot. Hardwood and rough-sawn lumber are almost always priced and sold by the board foot rather than by the plank or the linear foot, because it is a measure of volume that fairly reflects how much wood you actually get. Enter the number of boards and each board's thickness, width, and length, and this tool computes the board feet per piece, the total board feet for the whole batch, and the total cost if you supply a price. Whether you are buying oak for a table, walnut for cabinets, or pine for a project, it takes the guesswork out of ordering and budgeting.
Because the formula mixes inches and feet, board-foot math is easy to get wrong by hand. This calculator handles the units for you and even lets you enter dimensions in centimeters or millimeters if that is what you have, converting everything correctly behind the scenes.
A board foot (abbreviated BF or bd. ft.) is a unit of volume used to measure lumber. One board foot equals the volume of a piece of wood that is 1 inch thick, 12 inches wide, and 1 foot long — that is 144 cubic inches of wood. It is important to understand that a board foot measures volume, not surface area or length. A plank that is 1 inch by 12 inches by 1 foot is one board foot; so is a piece 2 inches thick, 6 inches wide, and 1 foot long, because it contains the same amount of wood. This volume-based approach is why the board foot is the fair and standard way to price lumber: a thick, wide board rightly costs more than a thin, narrow one of the same length.
The board foot formula for a single piece, using the common mix of inches and feet, is:
board feet = thickness (in) × width (in) × length (ft) ÷ 12
The division by 12 converts the mixed units into board feet. If you prefer to work entirely in inches, the equivalent formula is thickness × width × length, all in inches, divided by 144 (since there are 144 cubic inches in a board foot). For several identical boards, multiply the per-piece figure by the number of boards to get the total:
total board feet = board feet per piece × number of boards
total cost = total board feet × price per board foot
The calculator applies these formulas automatically and shows each step, so you can see exactly how the numbers come together.
Suppose you are buying 5 boards, each 1.25 inches thick, 10 inches wide, and 8 feet long, at a price of $4.15 per board foot. The calculation runs like this:
So five such boards give you about 41.67 board feet of lumber costing roughly $172.92. These are the default values loaded into the calculator, so you can press Calculate to see the full breakdown, then change any figure for your own order.
One of the most common sources of confusion in lumber math is the difference between nominal and actual dimensions. A "2×4" is a nominal size — the size of the rough board before it was dried and planed smooth — and its actual finished size is only about 1.5 inches by 3.5 inches. For softwood construction lumber sold by the piece, board feet are traditionally figured from the nominal size. For hardwoods sold by the board foot, the thickness is often expressed in quarters of an inch: 4/4 ("four-quarter") means 1 inch, 5/4 means 1.25 inches, 8/4 means 2 inches, and so on, usually referring to the rough thickness. When you calculate board feet, use the dimensions your supplier prices by — ask whether they charge on nominal or actual size — so your estimate matches the invoice. This calculator lets you enter whatever thickness and width you were quoted.
Hardwood dealers describe board thickness in quarters of an inch, a system that trips up many first-time buyers. The number over four tells you the thickness in inches: 4/4 = 1″, 5/4 = 1.25″, 6/4 = 1.5″, 8/4 = 2″, 10/4 = 2.5″, and 12/4 = 3″. So a "5/4 board" is nominally 1.25 inches thick — exactly the thickness in our worked example. This tradition dates back to sawmills cutting green (undried) lumber, leaving extra thickness for the shrinkage and planing that follow. When you order 4/4 lumber and plane it smooth, you typically end up with a finished board around 13/16″ thick, but you pay for the full 4/4. Enter the quarter thickness (as a decimal) into the calculator to match how you will be billed.
Selling lumber by the board foot is fairer than selling it by the plank or the running foot because it accounts for all three dimensions. Two boards can be the same length yet contain very different amounts of wood if one is thicker or wider. Pricing by volume means you pay in proportion to the actual material you receive, and it lets dealers quote a single price for a species regardless of the exact sizes in stock. For buyers, thinking in board feet makes it easy to compare prices between suppliers, estimate the cost of a project, and know whether a "deal" on a stack of odd-sized boards is really a bargain. It is the common language of the lumber world, from small sawmills to large distributors.
When you walk into a hardwood dealer, prices are quoted per board foot and often vary by species, grade, and thickness — thicker stock like 8/4 usually costs more per board foot than 4/4 because it takes longer to dry and yields fewer boards per log. To budget a project, add up the board feet of every piece you need, add a generous allowance for waste, and multiply by the price per board foot for each species. This calculator makes that first step painless: enter each board size and quantity, read off the total board feet, and drop in the price to see the cost. Doing this before you visit the yard means you arrive knowing roughly what your wood should cost, so you can spot a fair quote and avoid over- or under-buying.
Three "feet" measurements come up when buying wood, and confusing them leads to costly ordering mistakes:
Use board feet when thickness varies and you are paying for the actual volume of wood, such as buying hardwood boards of different sizes. Use linear feet when the profile is constant and only length matters. Use square feet for sheet goods and surface coverage. This calculator focuses on board feet, the trickiest of the three because it involves all three dimensions.
If you are dealing with whole logs rather than sawn boards, the board-foot yield is estimated with special log rules such as the Doyle, Scribner, or International 1/4-inch rules, which account for the wood lost to sawdust, bark, and slabs when a round log is cut into rectangular boards. These rules give a lower figure than the raw volume of the log, because not every cubic inch of a log becomes usable lumber. This calculator is designed for finished or dimensioned boards where you already know the thickness, width, and length — not for standing timber or logs. Once a log has been milled into boards, enter each board's dimensions here to total up the yield.
Here are the board feet for some standard single boards, which you can confirm in the calculator:
Notice that doubling any one dimension doubles the board feet, since the measure is a simple product of the three sizes. That linear behavior makes board feet easy to scale up once you have calculated one board.
A board foot is a unit of lumber volume equal to a board 1 inch thick, 12 inches wide, and 1 foot long — that is, 144 cubic inches of wood. Lumber, especially hardwood, is priced by the board foot.
Multiply thickness in inches by width in inches by length in feet, then divide by 12. For example, a board 1.25″ × 10″ × 8 ft is 1.25 × 10 × 8 ÷ 12 = 8.33 board feet.
Using nominal dimensions, a 2×4 that is 8 feet long is 2 × 4 × 8 ÷ 12 = 5.33 board feet. Note that softwood is often sold by the piece rather than the board foot.
These express hardwood thickness in quarters of an inch: 4/4 is 1 inch, 5/4 is 1.25 inches, and 8/4 is 2 inches. Enter the decimal thickness (for example, 1.25 for 5/4) into the calculator.
No. A square foot measures surface area, while a board foot measures volume (it includes thickness). Two boards with the same square footage can differ in board feet if they are different thicknesses.
Multiply the total board feet by the price per board foot. This calculator does it for you when you enter a price — for 41.67 BF at $4.15, the cost is $172.92.
This Board Foot Calculator is provided for general informational and estimating purposes. Results depend on the dimensions you enter and whether your supplier prices by nominal or actual size. Always confirm quantities and pricing with your lumber supplier before ordering.