Quickly estimate lumber volume and cost using the board foot formula.
Board feet by lumber size and length (feet)
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* Values calculated using: Board Feet = Thickness (in) × Width (in) × Length (ft) / 12. Nominal dimensions used.
Board Feet = Thickness (in) × Width (in) × Length (ft) / 12
Where all measurements use nominal lumber dimensions
T × W × L / 12
Board feet for one piece
(T × W × L / 12) × N
Multiply by number of boards
Total BF × Price/BF
Estimate your lumber cost
Lumber is sold by nominal size (e.g., 2×4), but actual dimensions are smaller after drying and planing (e.g., 1.5" × 3.5"). Board feet are traditionally calculated using nominal dimensions. When precision matters — such as for hardwood purchases — confirm whether your supplier quotes nominal or actual sizes.
A board foot is the standard unit of measurement for lumber volume in the United States and Canada. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide, and 12 inches long — or 144 cubic inches of material. Unlike square footage, which only measures area, board footage accounts for the full three-dimensional volume of a board.
Whether you're purchasing hardwood for a furniture project, framing lumber for construction, or specialty wood for cabinetry, understanding board feet helps you accurately estimate material needs and compare pricing across different board sizes and suppliers.
Board feet measure the actual volume of lumber, making it easy to compare boards of different sizes.
Hardwood lumber is priced per board foot, giving you a consistent way to budget and compare costs.
Calculate exactly how much lumber you need before heading to the supplier — no guesswork involved.
Calculating board feet is straightforward. The formula multiplies three dimensions and divides by 12 to convert to the standard board foot unit. Here's how to use our calculator step by step:
Measure the thickness of your board in inches. For standard lumber, use the nominal size (e.g., 2 inches for a "two-by" board). For rough-sawn hardwood, measure the actual thickness.
Record the width of the board in inches. Again, use nominal dimensions for dimensional lumber or actual measurements for custom-milled wood.
Measure the total length of the board in feet. This is the only dimension entered in feet — thickness and width stay in inches.
Specify how many pieces you need and optionally enter the price per board foot. The calculator will give you total board feet and estimated cost instantly.
Say you need 5 boards, each 8 feet long, 10 inches wide, and 1.25 inches thick. Per piece: 1.25 × 10 × 8 / 12 = 8.33 BF. For 5 pieces: 8.33 × 5 = 41.67 BF. At $4.15 per board foot, the total cost is $172.92.
Lumber measurements can be confusing because different units are used for different purposes. Here's how board feet compare to other common measurements you'll encounter:
| Unit | Measures | Best For |
|---|---|---|
| Board Foot | Volume (144 in³) | Pricing hardwood & specialty lumber |
| Linear Foot | Length only (12 in) | Trim, molding, uniform-size boards |
| Square Foot | Area (144 in²) | Flooring, plywood, sheet goods |
| Cubic Foot | Volume (1,728 in³) | Bulk materials, firewood |
Board foot calculations come up in a wide range of woodworking, construction, and lumber purchasing scenarios. Here are the most common situations:
Price cherry, walnut, oak, and other hardwoods sold by the board foot at lumber yards.
Estimate material needs for tables, shelving, cabinets, and custom woodworking builds.
Prepare accurate material takeoffs for framing, decking, and structural lumber orders.
Compare pricing between different board sizes, species, and suppliers on an equal basis.
Teach and learn lumber measurement fundamentals in shop classes and apprenticeships.
Manage lumber yard inventory and track stock levels using standardized board foot units.
It depends on the length. A 2×4 that is 8 feet long contains 5.33 board feet (2 × 4 × 8 / 12). A 12-foot 2×4 contains 8 board feet. Use our reference table for quick lookups.
A board foot measures volume (1" × 12" × 12"), while a linear foot measures only length (12 inches). Board feet account for the width and thickness of the lumber, making them more useful for comparing different board sizes.
Traditionally, board feet are calculated using nominal dimensions (e.g., 2×4, not 1.5×3.5). However, when purchasing rough-sawn hardwood, actual measurements are typically used. Always confirm with your supplier which convention they follow.
Divide the number of board feet by 12. For example, 120 board feet equals 10 cubic feet. This is because one board foot is 1/12 of a cubic foot (1" thick × 1' × 1' = 144 in³ = 1/12 ft³).
MBF stands for "thousand board feet" (M is the Roman numeral for 1,000). It's commonly used in the lumber industry when dealing with large volumes. For example, 5 MBF equals 5,000 board feet.