Free board foot calculator. Enter thickness, width, length and piece count to get total board feet and lumber cost for your project.
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Enter thickness in inches, width in inches, length in feet, piece count, and price per board foot. The calculator multiplies thickness by width by length and divides by 12 to get board feet per piece, multiplies by pieces for total board feet, and multiplies by price per board foot for total cost.
A board foot is a unit of lumber volume, not a unit of length or area. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long, which is 144 cubic inches of wood. This board foot calculator uses that definition for every result, so the same piece always gives the same volume no matter who measures it. Lumber yards in the United States and Canada use board feet for pricing hardwood and rough lumber, and the unit is often shortened to BF or FBM, while 1000 board feet is written as MBF. Because a board foot counts thickness as well as width and length, two boards of the same length can hold very different amounts of wood. That is why a lumber volume calculator based on board feet is fairer for buying wood than a simple length measurement, and why this woodworking lumber calculator is useful for both small home projects and larger building work.
The board foot formula is simple once the units are clear. Board feet per piece equals thickness in inches multiplied by width in inches multiplied by length in feet, divided by 12. If every dimension is measured in inches, divide by 144 instead, and the answer is the same. For example, a board that is 2 inches thick, 6 inches wide, and 8 feet long gives 2 times 6 times 8 divided by 12, which is 8 board feet. A nominal 2x4 board that is 8 feet long gives 2 times 4 times 8 divided by 12, which is 5.33 board feet when nominal sizes are used. This board feet formula works for framing lumber, deck boards, furniture stock, and rough sawn hardwood, provided the thickness, width, and length are entered in the units the formula expects. Mixing feet and inches is the most common mistake, so check each input before trusting the result.
Many builders ask how to calculate board feet for multiple pieces, and the method is a short extension of the single board formula. First, work out the board feet per piece from its thickness, width, and length. Then multiply that figure by the number of identical pieces to get the total board feet for the order. If an order contains different sizes, calculate each size separately and add the totals together, because a bundle total is only correct when every unique size is counted on its own. For example, ten boards at 4 board feet each give 40 board feet in total, and twenty boards at 5 board feet each give 100 board feet in total. This approach also works for board feet for deck boards, where many identical boards are ordered at once, and for board feet for furniture projects, where several sizes may be needed for one piece of furniture. Always confirm the piece count with the cutting list before ordering.
The nominal vs actual lumber size difference causes more confusion than any other part of lumber buying. A nominal size is the rough cut name given to a board before drying and planing, while the actual size is what you measure on the finished board. A nominal 2x4, for example, actually measures 1.5 inches by 3.5 inches after surfacing, and a nominal 2x6 actually measures 1.5 inches by 5.5 inches. For buying and sawmill board foot pricing, most suppliers count board feet on the nominal size, so a nominal 2x4 board that is 8 feet long is counted as 5.33 board feet, even though its actual volume is 3.5 board feet. For estimating the real volume of wood in a finished project, use actual sizes instead. The safest habit is to ask the supplier which size convention the quote uses, and to use the same convention in this calculator, so the estimate and the invoice agree.
A board foot vs linear foot comparison shows why the right unit matters. A linear foot measures length only, so 20 linear feet of trim is 20 feet long no matter how wide or thick the trim is. That unit suits trim, molding, baseboards, and some fencing, where price follows length. A board foot vs square foot comparison is different again: a square foot measures area, which suits flooring, plywood, and sheet goods, where thickness is standard or sold separately. A board foot measures volume, because it multiplies thickness, width, and length together. That makes it the right unit when thickness changes the amount of wood you receive, as it does with hardwood boards, slabs, and dimensional lumber. Choosing the wrong unit can make a quote look cheaper or dearer than it really is, so check whether the supplier prices by board foot, linear foot, square foot, or per piece before comparing prices.
A board foot chart saves time when the same sizes are ordered again and again. Using nominal sizes, common lumber sizes board feet values include: a 1x6 board at 8 feet is 4 board feet; a 2x4 board at 8 feet is 5.33 board feet, and the familiar question of how many board feet in a 2x4x8 has the same answer, 5.33 board feet on nominal sizes; a 2x6 board at 8 feet is 8 board feet; a 2x8 board at 8 feet is 10.67 board feet; a 2x10 board at 8 feet is 13.33 board feet; a 2x12 board at 8 feet is 16 board feet; and a 4x4 post at 8 feet is 10.67 board feet. Many buyers also use the chart for longer boards, where board feet rise in proportion to length, so a 2x6 at 12 feet is 12 board feet and a 2x6 at 16 feet is 16 board feet. Use the chart as a quick check, and use the calculator for exact sizes, mixed orders, and total cost.
A lumber cost calculator is only as useful as the price it is given, so start with a real quote for price per board foot from the supplier. Total cost equals total board feet multiplied by price per board foot, which is why a small change in price has a large effect on a big order. A board foot cost estimate made this way lets a buyer compare suppliers fairly, because two quotes for different board sizes can be reduced to the same price per board foot. Sawmill board foot pricing often varies by species, grade, width, and length, and wide or long boards may carry a premium, so confirm whether the quoted price covers the exact sizes in the order. Enter the quoted price per board foot in the calculator, choose the currency that matches the quote, and treat the result as an estimate for budgeting, not as a supplier invoice. Confirm delivery, tax, and cutting charges separately, because they are not part of board foot pricing.
Hardwood is often sold by quarter thickness, and the quarter sawn hardwood thickness 4/4 system is the key to reading those quotes. In this system, 4/4 means 1 inch of rough thickness, 5/4 means 1.25 inches, 6/4 means 1.5 inches, and 8/4 means 2 inches, all measured before surfacing. Rough sawn hardwood is counted on its rough thickness, so a 4/4 board is entered as 1 inch even if it finishes thinner after planing. A board feet waste allowance should also be added in planning, because cuts, knots, defects, and grain matching all reduce usable yield. Many woodworkers allow extra material for furniture work, and a similar allowance helps with deck and framing orders. For volume conversion, board feet to cubic feet is simple: divide total board feet by 12, because one board foot is one twelfth of a cubic foot. One cubic metre is about 424 board feet, which helps when comparing quotes from suppliers who sell by cubic volume.
A board foot is a unit of lumber volume equal to a piece of wood 1 inch thick, 12 inches wide, and 12 inches long, which is 144 cubic inches. It is the standard unit for pricing hardwood and rough lumber in the United States and Canada, and it is often shortened to BF or FBM.
Multiply thickness in inches by width in inches by length in feet, then divide by 12. If all dimensions are in inches, divide by 144 instead. For example, a 2 inch by 6 inch board that is 8 feet long gives 2 times 6 times 8 divided by 12, which is 8 board feet.
Many people ask how many board feet are in a nominal 2x4x8 board, and the answer on nominal sizes is 5.33 board feet, from 2 times 4 times 8 divided by 12. Using actual finished sizes of 1.5 inches by 3.5 inches, the same board holds 3.5 board feet of real wood volume.
Nominal size is the rough cut name, such as 2x4, given before drying and planing. Actual size is the finished measurement, such as 1.5 inches by 3.5 inches for a 2x4. Most suppliers price board feet on nominal size, so ask which convention a quote uses and match it in the calculator.
Board feet measure volume, because they include thickness, width, and length. Linear feet measure length only, so a long thin board and a long thick board of the same length have the same linear feet but different board feet. Use board feet for hardwood and dimensional lumber, and linear feet for trim and molding priced by length.
Square feet measure area, which is length multiplied by width, and suit flooring and sheet goods. Board feet measure volume, which adds thickness, so they suit lumber where thickness changes how much wood is supplied. A board foot is not the same as a square foot, even when the surface area matches.
Calculate board feet per piece first, then multiply by the number of identical pieces to get total board feet. For a bundle with different sizes, calculate each size separately and add the totals. This gives the correct total board feet for the whole order, which can then be multiplied by price per board foot for total cost.
Total cost equals total board feet multiplied by price per board foot. For example, 80 board feet at 3.50 per board foot gives a total cost of 280 in the selected currency. Use this board foot cost estimate for budgeting, and confirm delivery, tax, and cutting charges with the supplier separately.
The formula is the same for hardwood and softwood, but the buying conventions differ. Hardwood is usually sold by the board foot and by quarter thickness, such as 4/4 for 1 inch rough thickness, while softwood framing lumber is often sold by nominal size or per piece. Rough sawn hardwood is counted on its rough thickness, not its finished thickness.
To convert board feet to cubic feet, divide total board feet by 12, because one board foot is one twelfth of a cubic foot. For waste, allow extra board feet beyond the exact total for cuts, knots, defects, and grain matching, especially for furniture projects. The calculator gives the exact total, so add your chosen waste allowance to the result when ordering.