Wood Units Calculator: Convert Board Feet, Linear Feet, Square Feet and Cubic Feet
Enter a board’s length, width, thickness, and quantity to instantly convert between the four measurement units woodworkers and lumber yards actually use — board feet (BF = thickness in. x width in. x length ft / 12), linear feet, square feet, and cubic feet — so you know exactly what you’re paying for and how much material to order.
Quick Answer
Enter a board’s length, width, thickness, and quantity to instantly convert between the four measurement units woodworkers and lumber yards actually use — board feet (BF = thickness in. x width in. x length ft / 12), linear feet, square feet, and cubic feet — so you know exactly what you’re paying for and how much material to order.
Wood Units Calculator: Convert Board Feet, Linear Feet, Square Feet and Cubic Feet
Enter your values below for an instant result, then see the formula, worked example, and common mistakes.
Enter your board dimensions, then click calculate.
How to Use This Calculator
This is the long dimension of the board, measured in feet — most lumber is sold in even lengths like 6, 8, 10, or 12 feet.
Width is the board’s face width; thickness is the nominal (or actual, for hardwood) thickness. A rough hardwood board might be sold as “4/4” (four-quarter, meaning 1 in nominal thickness).
The calculator multiplies per-board board feet by quantity to give you a running total for an entire order.
Board feet is what most hardwood is priced by; linear feet is common for trim and molding sold by length only; square feet covers flooring, paneling, and sheet goods; cubic feet is total solid wood volume, useful for weight or shipping estimates.
Formula
Board Feet = (Thickness in inches x Width in inches x Length in feet) / 12. One board foot equals 144 cubic inches of wood — the volume of a board 1 in thick, 12 in wide, and 12 in (1 ft) long. Linear feet is simply the board’s length, ignoring width and thickness. Square feet = (Width in feet) x (Length in feet), the surface area only. Cubic feet = Board Feet / 12, since one cubic foot of wood equals exactly 12 board feet.
Reference Table: Which Unit Applies to Which Material
| Unit | Accounts for thickness? | Typical use |
|---|---|---|
| Board feet (BF) | Yes | Hardwood lumber, rough-sawn stock, pricing by volume |
| Linear feet | No (length only) | Trim, molding, baseboard, fencing rails — fixed cross-section items |
| Square feet | No (area only) | Flooring, plywood/sheet goods, paneling, decking |
| Cubic feet | Yes (full volume) | Total solid wood volume, weight estimates, shipping/storage |
Common Mistakes to Avoid
- Using actual (finished) thickness for softwood dimensional lumber pricing when the yard prices by nominal thickness — a nominal 2×4 is actually 1.5 x 3.5 in, but is typically still priced/counted using its 2×4 nominal size.
- Confusing linear feet with board feet — a 10 ft piece of 1×12 trim is 10 linear feet but 10 board feet, while a 10 ft piece of 1×4 is still 10 linear feet but only about 3.33 board feet, since linear feet ignores width entirely.
- Forgetting that hardwood is typically priced and measured using actual thickness (not nominal), since hardwood is usually sold rough-sawn rather than pre-dimensioned like construction softwood.
- Mixing metric and imperial dimensions without converting first — this calculator assumes feet for length and inches for width/thickness.
When the Estimate May Be Wrong
This calculator uses nominal thickness and width as entered — if your hardwood board’s actual measured thickness differs from its nominal size (common with rough-sawn stock), use the actual measured dimensions for the most accurate board-foot total, since that is what most hardwood suppliers bill against.
FAQs
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches — the size of a board 1 inch thick, 12 inches wide, and 12 inches (1 foot) long. It’s the standard unit for pricing hardwood.
How is board feet different from square feet?
Square feet measures only surface area (length x width) and ignores thickness, while board feet is a volume measurement that includes thickness — a thicker board has more board feet even at the same length and width.
Do lumber yards use nominal or actual dimensions for board feet?
For standard softwood dimensional lumber (like 2x4s), nominal dimensions are typically used for board-foot counting. For hardwood, actual measured thickness is standard practice since hardwood is usually sold rough or S2S rather than pre-dimensioned.
How many board feet are in a cubic foot?
Exactly 12 board feet equal one cubic foot, since a board foot is 144 cubic inches and a cubic foot is 1,728 cubic inches (1,728 / 144 = 12).
Sources and Methodology
Board foot formula (T x W x L / 12) and the 144-cubic-inch/12-board-feet-per-cubic-foot conversion are standard, universally used lumber industry definitions confirmed against Inch Calculator’s Board Footage Calculator, Sustainable Lumber Co.’s board/lineal/square foot comparison guide, and Wikipedia’s Board Foot reference. Nominal-vs-actual dimension convention for softwood vs. hardwood follows standard industry practice as described by multiple lumber calculator sources.
