Board Foot Calculator

Frequently Asked Questions

How is a board foot calculated?

Board feet = (thickness in × width in × length in) ÷ 144, since one board foot is 144 cubic inches (12 × 12 × 1 in). A board 1 in × 6 in × 96 in is (1 × 6 × 96) ÷ 144 = 4 board feet.

How do I price lumber by the board foot?

Cost = board feet × price per board foot. At $6/bf, that 4 bf board costs 4 × 6 = $24, before any waste or surfacing charges.

Do I use rough or finished thickness?

Hardwood is priced by its rough (nominal) thickness in quarters - 4/4 means 1 in rough even though surfaced stock measures about 13/16 in. Calculate board feet from the rough dimensions you are billed for.

How much extra should I buy for waste?

Add 15–30% to your net board-foot total for defects, trimming, and grain selection - more for figured boards or when matching color. So a 20 bf project might mean ordering ~25 bf.

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How This Calculator Works

Hardwood lumber is not sold by the running foot like dimensional softwood - it is sold by the board foot, a unit of volume equal to a piece 1 inch thick, 12 inches wide, and 12 inches long (144 cubic inches). This calculator computes board feet from the three dimensions of a board, multiplies by how many identical boards you are buying, and turns the total into a price using a dollars-per-board-foot rate. Because lumberyards quote length in either feet or inches, you can switch between the two and the formula adjusts automatically. The thickness is the rough nominal thickness in inches (a "4/4" board counts as 1 inch, "8/4" as 2 inches, even after surfacing thins it slightly), and the width is the actual face width. Enter the per-board-foot price and the tool gives you the total cost so you can compare boards and budget a project before you load the truck.

Formula / Method

Board feet for one board is volume in the special board-foot unit. With length in feet: BF = (thickness in × width in × length ft) ÷ 12. With length in inches: BF = (thickness in × width in × length in) ÷ 144. Both express the same volume - the ÷12 version folds a 12 in-per-foot conversion into the divisor (144 ÷ 12 = 12). Total board feet = BF per board × quantity, and total cost = total board feet × price per board foot. Thickness and width must be positive, length positive, quantity at least one, and price non-negative, or the calculator returns a friendly message rather than a misleading zero or NaN. Note that yards typically price by the rough (pre-surfaced) dimensions, so use the nominal thickness even if the surfaced board measures a little less.

Worked Example

You want four 4/4 (1 inch) red oak boards, each 6 inches wide and 8 feet long, at $5.00 per board foot. One board: BF = (1 × 6 × 8) ÷ 12 = 48 ÷ 12 = 4.000 board feet. Four boards: 4 × 4 = 16.000 board feet. Cost = 16 × $5.00 = $80.00. If the same board were quoted as 96 inches long instead of 8 feet, the inch formula gives (1 × 6 × 96) ÷ 144 = 576 ÷ 144 = 4.000 board feet - identical, as it must be. Step up to 8/4 (2 inch) stock and each board doubles to 8 board feet, so the same order would cost $160.00.

Common Mistakes

Mixing units - entering length in feet while the mode is set to inches (or vice versa) inflates or shrinks the total twelvefold.

Using the surfaced thickness instead of the nominal/rough thickness the yard actually charges for.

Forgetting that 4/4, 5/4, 8/4 are quarter-inch thickness fractions: 4/4 = 1", 5/4 = 1.25", 8/4 = 2".

Confusing board feet (a volume) with lineal feet (a length) - only board feet account for width and thickness.

Buying exactly the calculated board feet with no allowance for defects, snipe, and milling waste - add 15–30%.

Tips & FAQ

How much extra should I buy? Hardwood comes with knots, checks, and wane you will cut around, so add 15% for clear straightforward parts and 30% or more for short defect-free pieces or figured stock. What does 4/4 mean? It is the rough thickness in quarter-inches: 4/4 is one inch rough, surfaced to about &frac1316; inch; always pay for the rough number. Why is wide stock pricier per board foot? Wide clear boards come from larger logs and are scarcer, so premium widths often carry an upcharge the base rate here will not show. Does length affect the rate? Sometimes - very long boards can cost more per board foot; check the yard's pricing. How do I price softwood? Dimensional softwood is usually sold by the piece or lineal foot, so board-foot math is mainly for hardwoods and rough lumber. What about partial board feet? Yards typically round the tally per board or per order; treat the decimal here as the exact volume and expect minor rounding at the till. Use this as a budgeting estimate and confirm pricing and surcharges with your supplier.

Frequently Asked Questions

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