Calculate Lumber Board Feet
Enter the rough lumber dimensions. Results update instantly.
What Is a Board Foot?
A board foot is a volume measurement used to sell hardwood lumber. One board foot equals a piece of wood that is 1 inch thick, 12 inches wide and 12 inches long.
That does not mean the board has to be exactly 1 × 12 × 12. A longer, narrower board can contain the same volume. The calculator converts the board's thickness, width and length into that common measurement so boards of different sizes can be priced consistently.
How to Calculate Board Feet
When thickness and width are measured in inches and length is measured in feet, use this formula:
For example, a board that is 1 inch thick, 8 inches wide and 8 feet long contains:
If you buy three identical boards, multiply 5.33 by 3 for a total of about 16 board feet.
Board Foot Examples
For rough hardwood, the lumber yard may use established industry measuring and rounding practices rather than simply multiplying the nominal dimensions shown on a bin label. Ask the dealer how they measure and tally stock if the invoice differs slightly from your estimate.
Using 4/4, 5/4, 6/4 and 8/4 Lumber
Hardwood thickness is often written in quarters. 4/4 means four quarters, or roughly 1 inch before surfacing. 5/4 is roughly 1¼ inches, 6/4 is roughly 1½ inches, and 8/4 is roughly 2 inches.
Those are rough-lumber thickness categories, not guaranteed finished dimensions. Surfacing and flattening remove material, so a 4/4 board will usually finish thinner than 1 inch. The calculator's preset buttons use the nominal rough thickness because that is the most useful starting point when estimating hardwood purchases.
Board Feet vs. Linear Feet
Linear feet measure only length. Board feet measure volume, so thickness and width matter too. Two boards can both be 8 feet long but have very different board-foot totals if one is wider or thicker.
This is one reason hardwood shopping feels different from buying dimensional construction lumber at a big-box store: hardwood is commonly priced by volume rather than simply by the piece.
Estimating Hardwood Lumber Cost
If your lumber yard lists a species at a price per board foot, enter that price in the calculator. The tool multiplies your total board feet by the price to give you a quick material-cost estimate.
The estimate does not include sales tax, milling charges, minimum-purchase rules, special-width premiums or waste. For project planning, also allow extra material for defects, grain matching and milling.
Board Foot Calculator FAQ
Do I use rough or finished dimensions?
For buying rough hardwood, start with the rough or nominal dimensions used by the lumber dealer. If you are calculating material you already have, use its actual measured dimensions.
How many board feet are in a 1 × 8 × 8 board?
A board that is actually 1 inch thick, 8 inches wide and 8 feet long contains about 5.33 board feet.
Does 4/4 lumber equal exactly 1 inch thick?
4/4 describes a rough thickness category of roughly 1 inch. Once surfaced and flattened, the finished board will usually be thinner.
Why can a lumber-yard tally differ from my calculator?
Dealers may follow industry measurement, minimum-width and rounding conventions. The calculator is best used as an estimating tool; the dealer's tally determines the actual invoice.
Related Hardwood & Workshop Guides
- How to Buy Hardwood Lumber: A Beginner’s Guide to the Lumber Yard — understand 4/4 and 8/4 stock, rough-sawn lumber, surfacing, grades and grain cuts.
- Wood Routers Buying Guide — choosing a router for shaping and joinery.
- Best Table Saw Under $500 — compare portable saws for a home workshop.
Research Sources & Methodology
The calculator uses the standard board-foot relationship of 144 cubic inches per board foot. Hardwood dealers may use additional tallying and rounding conventions, so treat results as planning estimates and confirm final quantities with the seller.
Bottom Line
For most hardwood shopping, board feet are simply a way to compare and price boards by volume. Enter thickness, width, length and quantity above to get a quick estimate before you head to the lumber yard.
Remember
- 4/4 is roughly 1 inch before surfacing.
- Width and thickness affect board-foot cost.
- Add waste for milling and defects.
- Dealer tallying practices can vary.