What Is a Board Foot?
A board foot is the standard unit for measuring and pricing rough lumber in North America. One board foot equals a piece of wood 12 inches long, 12 inches wide, and 1 inch thick — or 144 cubic inches. Lumber yards, sawmills, and hardwood dealers price stock by the board foot, so understanding the measurement is essential for accurate project budgeting.
Our board foot calculator lets you enter thickness, width, and length for each piece, add multiple sizes to a cut list, and see the total board footage with an optional cost estimate. No rounding surprises — results update instantly.
Board Foot Formula
The formula is the same whether you measure in inches or feet:
Board Feet = (Thickness × Width × Length) / 144
(all dimensions in inches)
For example, a single 8/4 (2″ thick) walnut board that is 8 inches wide and 96 inches long contains 10.67 board feet. At $12 per board foot, that piece costs about $128.
Common Lumber Thicknesses
Rough lumber is sold in quarter-inch increments. Here are the most common thicknesses and their dressed (surfaced) equivalents:
| Rough | Actual (S2S) | Common Use |
|---|---|---|
| 4/4 (1") | 13/16" | Shelving, trim, small projects |
| 5/4 (1¼") | 1-1/16" | Decking, tabletops |
| 6/4 (1½") | 1-5/16" | Furniture legs, workbenches |
| 8/4 (2") | 1¾" | Heavy-duty furniture, cutting boards |
| 12/4 (3") | 2¾" | Turning blanks, mantels |
Frequently Asked Questions
How many board feet in a 2×4?
A standard 8-foot 2×4 contains 5.33 board feet (1.5″ × 3.5″ × 96″ / 144). However, dimensional lumber like 2×4s is usually sold by the linear foot, not the board foot. Board foot pricing is mainly used for rough hardwood and specialty wood.
What is the difference between board feet and linear feet?
Linear feet measures only length, regardless of width or thickness. Board feet accounts for all three dimensions. A 10-foot board that is twice as wide contains twice the board feet but the same linear footage.
Should I calculate board feet using nominal or actual dimensions?
Use the rough (nominal) thickness when buying from a sawmill or hardwood dealer — that is how they price it. If the lumber is already surfaced, use the actual thickness so your volume and cost estimate is accurate.