Calculate board feet for one or many boards from thickness, width and length, with a built-in lumber cost estimator from price per board foot.
Your results will appear here.
Enter your values and press Calculate.
The calculator multiplies the board's thickness in inches by its width in inches by its length in feet, then divides by 12 to get the board feet in a single board. It multiplies that by the number of boards for the total board footage of your order. When you enter a price per board foot, it multiplies the total board footage by that price to estimate the total lumber cost. Enter 0 as the price per board foot to skip the cost estimate. The page uses nominal dimensions for the billing reference table because lumberyards bill on nominal sizes, while the calculator itself works with whatever dimensions you enter, nominal or actual. These are planning estimates, not professional advice; confirm final quantities and pricing with your supplier.
A board foot (BF) is a unit of volume used to measure and price lumber, not a unit of length. One board foot equals 144 cubic inches, which is the volume of a board 12 inches long, 12 inches wide and 1 inch thick. You can also think of it as 1/12 of a cubic foot. Sawmills, lumberyards and hardwood dealers across the USA and Canada price hardwood lumber by the board foot, because two boards can be the same length yet hold very different amounts of wood. Board footage includes thickness, while square footage only covers length and width, which is why board feet are the standard unit for lumber pricing.
The board foot formula is: board feet = thickness (in) × width (in) × length (ft) / 12. Watch the units: thickness and width are in inches, length is in feet. The division by 12 normalizes the length in feet against the width and thickness in inches, which is why the mixed-units formula divides by 12 instead of 144. There are two equivalent versions: if all three dimensions are measured in inches, divide by 144 instead; if all three are in feet, multiply by 12. Multiply the result by the number of identical boards to get the total board footage of your order.
Enter the thickness in inches, the width in inches, and the length in feet for one board, then the number of identical boards you need. The calculator shows the board feet in one board, the total board feet for the whole order, and an estimated total cost when you enter a price per board foot. Optionally add a price per board foot to turn the volume estimate into a budget figure. Measure carefully: thickness and width at the widest usable point, length in feet to the nearest decimal. Results update instantly, so you can test different lengths or board counts while standing at the lumber yard.
Example 1, one board: a board 1 inch thick, 6 inches wide and 8 feet long contains (1 × 6 × 8) / 12 = 4 board feet. Example 2, a common 2x4: using nominal dimensions, (2 × 4 × 8) / 12 = 5.33 board feet per 8-foot piece, so twelve 2x4s are 64 board feet. Example 3, an order of multiple boards with cost: ten 2x4 boards, each 8 feet long, measured at actual dimensions 1.5 × 3.5 inches, give (1.5 × 3.5 × 8) / 12 = 3.5 board feet each, 35 board feet total, and at $5.50 per board foot the lumber costs $192.50. Example 4, boards needed: a project needs 110 board feet after waste allowance, and each 1x8x10 board holds (1 × 8 × 10) / 12 = 6.67 board feet, so you need 17 boards. Always add 10 to 15 percent extra board footage for waste from cuts, defects and grain matching.
Lumber is sold by nominal size, which is the rough-cut dimension before drying and planing, but the actual finished board is smaller. A 2x4 is actually 1.5 by 3.5 inches; a 1x6 is actually 0.75 by 5.5 inches. Here is the catch: lumberyards and sawmills bill board feet using nominal dimensions, so a 2x4x8 is always billed as 5.33 board feet even though the actual wood volume is only 3.50 board feet. Quick reference for nominal board feet: 2x4 at 8 ft = 5.33 BF, at 12 ft = 8 BF, at 16 ft = 10.67 BF, at 24 ft = 16 BF; 2x6 at 8 ft = 8 BF; 2x8 at 8 ft = 10.67 BF; 2x12 at 8 ft = 16 BF; 4x4 at 8 ft = 10.67 BF. Keep this quick chart handy when checking a quote or planning a framing order. For accurate project volume use actual dimensions; for checking the yard's invoice, use nominal.
These three units measure different things, and mixing them up causes expensive mistakes. A board foot (BF) measures volume using all three dimensions: length, width and thickness. A linear foot (LF) measures length only: a board that is 10 feet long is 10 linear feet whether it is 2 inches wide or 12 inches wide. A square foot (SF) measures area using length and width, which suits flooring, plywood and wall coverage. Example: one 1-inch thick, 6-inch wide, 10-foot board equals 5 BF, 10 LF and 5 SF. How many board feet are in a linear foot? It depends on width and thickness: a 1-inch by 6-inch board holds 0.5 BF per linear foot, while a 2-inch by 12-inch board holds 2 BF per linear foot. To convert board feet to square feet, divide the board feet by the thickness in inches: 20 board feet of 1-inch lumber covers 20 square feet, but 20 board feet of 2-inch lumber covers only 10 square feet. This conversion is useful for flooring and wall paneling projects where you buy by the board foot but plan coverage by the square foot.
Multiply your total board feet by the price per board foot to estimate the lumber cost, which is what the cost estimator on this page does. Real lumber pricing also reflects species, grade, drying method, surfacing, width and region: common hardwood runs about $3.50 to $8.00 per board foot, while exotic species like black walnut can reach $7 to $14 per board foot or more. Remember that yards quote per nominal board foot, so you are paying for the wood that was planed away too. Compare quotes with the effective cost per board foot: divide the full invoice total, tax and delivery included, by the total board feet, and the lower number is the better deal. Read this section as your lumber yard buying guide: add 10 to 15 percent waste to the board footage first, then multiply by the price per board foot. These are planning estimates, not professional advice; confirm final pricing with your supplier.
Multiply the thickness in inches by the width in inches by the length in feet, then divide by 12. The board foot formula is: board feet = thickness (in) × width (in) × length (ft) / 12. For example, a board 2 inches thick, 6 inches wide and 8 feet long contains (2 × 6 × 8) / 12 = 8 board feet.
A board foot is a unit of lumber volume equal to 144 cubic inches, the volume of a board 12 inches long, 12 inches wide and 1 inch thick. Sawmills, lumberyards and hardwood dealers in the USA and Canada use board feet to price lumber, because it measures the actual volume of wood in boards of any size.
A 2x4x8 contains 5.33 board feet when calculated with nominal dimensions: (2 × 4 × 8) / 12 = 5.33 BF. Using the actual milled dimensions of 1.5 by 3.5 inches, the real wood volume is 3.50 board feet. Lumberyards price 2x4 dimensional lumber using the nominal figure of 5.33 BF.
A board foot measures volume using three dimensions (length, width, thickness) and equals 144 cubic inches, while a linear foot measures length only. A 10-foot board is always 10 linear feet no matter how wide or thick it is, but its board footage depends on all three dimensions. Use board feet when volume matters, like table tops, and linear feet for trim, molding and fencing.
Use nominal dimensions when checking the yard's invoice, because lumberyards bill board feet on nominal sizes: a 2x4 is billed as 2 by 4 even though it actually measures 1.5 by 3.5 inches. Use actual dimensions when you need the true volume of wood for your project, such as fitting boards into a design or estimating how much you can get from a rough-sawn log.
Divide the board feet by the thickness in inches: square feet = board feet / thickness (in). This works because board feet already include the thickness, so removing it leaves the area. For example, 20 board feet of 1-inch thick lumber covers 20 square feet, while 20 board feet of 2-inch thick lumber covers only 10 square feet.
The division by 12 normalizes the mixed units in the formula: length is measured in feet while width and thickness are measured in inches. Dividing by 12 converts the result to the correct volume of 144 cubic inches per board foot. When all three dimensions are measured in inches, you divide by 144 instead.
Add 10 to 15 percent extra board footage for waste from cuts, defects, knots and grain matching, then round up to whole boards. Rough lumber can lose another 5 to 15 percent to planer and jointer waste. For example, a project needing 100 board feet should be ordered as 110 to 115 board feet before converting to a board count.
Estimate concrete volume and bags needed for slabs, footings and columns.
Count the exact boards, rows, and linear feet your deck needs.
Count every 2x4 stud, plate board, and dollar before you frame a wall.
Estimate winter firewood in cords, face cords, and dollars.