Board Feet Calculator
Calculate board feet of lumber from thickness, width, length, and quantity — the volume unit hardwood is priced by — with the total cost.
كيفية استخدام هذه الحاسبة
- 1Enter the number of boards of the same size.
- 2Enter each board's thickness and width in inches.
- 3Enter the length in feet.
- 4Read the total board feet, and add a price per board foot for the cost.
طريقة الحساب
Board feet
1 board foot = 144 cubic inches board feet = thickness(in) × width(in) × length(ft) ÷ 12 or = thickness(in) × width(in) × length(in) ÷ 144 total = board feet per piece × number of pieces
A board foot is the standard unit of volume for lumber, particularly hardwood, and it equals 144 cubic inches — the amount of wood in a board one inch thick, twelve inches wide, and one foot long. To calculate it, multiply the thickness in inches by the width in inches by the length, then divide by 144 if the length is in inches, or by 12 if the length is in feet, since a foot is twelve inches. Multiplying by the number of identical boards gives the total volume. Because it measures volume rather than surface area or linear length, a board foot fairly captures the actual quantity of wood regardless of how it is dimensioned — a thick, narrow board and a thin, wide one can contain the same board footage. This is why lumberyards price hardwood per board foot: it charges for the wood itself, consistently across the wide variety of thicknesses and widths hardwood comes in.
مثال محلول
Ten boards, each 1 inch thick, 6 inches wide, and 8 feet long, contain 1 × 6 × 8 ÷ 12 = 4 board feet apiece, for a total of 40 board feet. At a price of, say, $5 per board foot, the lumber would cost $200 — priced by the volume of wood, not by the number of boards.
Board Feet Calculator: الدليل الكامل
A unit of volume, not area or length
The board foot confuses newcomers to woodworking because its name sounds like a linear or area measure, but it is neither — it is a measure of volume. One board foot is 144 cubic inches of wood, which happens to be the volume of a board one inch thick, one foot wide, and one foot long. The same board foot could equally be a piece two inches thick and half a foot wide, or any other combination multiplying to 144 cubic inches. What matters is the total volume of wood, not its particular shape.
This volumetric nature is exactly why the board foot exists as a unit. Hardwood lumber comes in a huge range of thicknesses and widths, often in rough, irregular sizes straight from the mill. Measuring it by the piece would be unfair, since pieces vary enormously, and measuring by linear foot would ignore thickness and width. Volume is the honest measure of how much wood you are actually getting, and the board foot packages that volume into a convenient unit sized to typical lumber. Once you internalise that it is 144 cubic inches, the calculation and its purpose both make sense.
Why hardwood is sold this way
The board foot is the currency of hardwood lumber for practical reasons rooted in how hardwood is produced and sold. Unlike the standardised dimensional softwood found at home centres — two-by-fours and the like, sold by the piece at fixed nominal sizes — hardwood is typically sold in random widths and lengths, cut to make the most of each log. A hardwood board might be any width the tree allowed, and boards are graded and priced by species and quality. Charging by volume, the board foot, is the only fair way to price such variable material.
This also explains a quirk that surprises people: hardwood thickness is often quoted in quarters of an inch, written as 4/4 (pronounced 'four quarter'), 5/4, 6/4, 8/4, and so on. A 4/4 board is nominally one inch thick, 8/4 is two inches, and these refer to the rough-sawn thickness before the board is planed smooth, which removes some material. When calculating board feet for pricing, the rough nominal thickness is usually used. Understanding the quarter system and the board-foot unit together is essential to buying hardwood, since a price tag reading '$6/BF' for '4/4 walnut' is meaningless without knowing both what a board foot is and what 4/4 signifies.
Buying and budgeting with board feet
For anyone planning a woodworking project, calculating board feet is the key to estimating both how much lumber to buy and what it will cost. A project's cut list — the pieces of a given thickness, width, and length needed — can be converted to board feet and summed, giving the total volume of wood required. Multiplying by the price per board foot for the chosen species yields the material cost, which is often the largest expense of a project and worth estimating before committing to a design or a wood.
A crucial practical point is to buy more than the finished project needs. Rough hardwood must be planed, jointed, and cut to final size, all of which remove material, and boards contain defects, checks, and grain that has to be worked around. Experienced woodworkers add a generous margin — commonly 20 to 40% over the calculated board feet — to account for this waste and for the inevitable mistake or change of plan. Buying too little means a return trip and possibly a batch of wood that does not match, since hardwood varies board to board. The board-foot calculation gives the baseline quantity; adding a sensible waste allowance on top turns it into a realistic shopping figure that avoids running short partway through a build.
الأسئلة الشائعة
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A board 1 inch thick, 6 inches wide, and 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet. Multiply by the number of identical boards for the total.
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches — the wood in a board 1 inch thick, 12 inches wide, and 1 foot long. It measures volume, not surface area or length, which is why the same board foot can take many shapes.
Why is hardwood sold by the board foot?
Because hardwood comes in random widths and lengths, unlike standardised softwood sold by the piece. Charging by volume — the board foot — is the fair way to price such variable material, so you pay for the actual amount of wood regardless of its dimensions.
How much extra lumber should I buy?
More than the calculated board feet — commonly 20 to 40% extra. Rough hardwood loses material when planed and cut to final size, boards have defects to work around, and mistakes happen. The board-foot figure is the baseline; add a waste margin so you don't run short mid-project.