Free estimate — verify against local code before building
Board Foot Calculator
Tally rough lumber in board feet line by line, then price the whole order.
What this calculator includes
Build a line-by-line lumber tally the way a hardwood dealer prices it. Each line takes a quantity, a quarters thickness (4/4 through 12/4, or a custom thickness in inches), a width in inches, and a length in feet; board feet per piece are thickness times width times length divided by 12. Price every line with its own dollars-per-board-foot rate or fall back to one global rate, add a waste allowance for defect and offcuts, and read the purchase total, cost, and average rate. Board feet always use the nominal rough dimensions, so surfaced stock still tallies at its rough size.
How to use this board feet calculator
- 01
List each lumber line
Enter a tally line for every size in the order: quantity, thickness, width in inches, and length in feet. Up to eight lines can be tallied and each shows its own board feet.
- 02
Use nominal rough dimensions
Choose the quarters thickness (4/4 = 1 in, 8/4 = 2 in) or enter a custom rough thickness. Board feet are always figured on the rough size before surfacing, so measure or order by the nominal dimension.
- 03
Price the tally
Enter one global dollars-per-board-foot rate, or give any line its own rate when species or grades differ. Hardwood pricing usually changes with thickness, grade, and species.
- 04
Add waste and buy
Add a waste allowance for defect, checking, and offcuts — 10-20% is common depending on grade — and buy the purchase total. Confirm the dealer's minimums and whether they tally in the rough or surfaced state.
Calculation sources and review
Primary references and formula assumptions are linked so you can verify them against the selected product, supplier, and adopted local requirements.
Internal formula review completed July 13, 2026. What this review covers
- National Hardwood Lumber Association — hardwood measurement and inspection rules (opens in a new tab)
Industry convention for quarters thickness and board-foot tally of rough hardwood lumber.
- USDA Forest Products Laboratory — Wood Handbook (opens in a new tab)
Reference for lumber measurement, nominal versus dressed sizes, and moisture content.
- American Hardwood Export Council — hardwood lumber guides (opens in a new tab)
Illustrated explanation of NHLA grades and board-foot measurement practice.
Frequently asked questions
What is a board foot?
A board foot is a volume unit equal to a piece 1 inch thick, 12 inches wide, and 1 foot long — 144 cubic inches. The formula is nominal thickness in inches times width in inches times length in feet, divided by 12.
What do 4/4, 5/4, and 8/4 mean?
Hardwood thickness is quoted in quarters of an inch of rough thickness: 4/4 is 1 inch, 5/4 is 1-1/4 inches, 6/4 is 1-1/2 inches, 8/4 is 2 inches, and 12/4 is 3 inches. After surfacing, actual thickness is less, but the tally stays nominal.
How many board feet are in a 2 by 6 by 8-foot board?
Using nominal dimensions, 2 x 6 x 8 / 12 = 8 board feet. Softwood construction lumber is usually sold by the piece or linear foot instead, but the same formula applies when it is priced by the board foot.
Why does a surfaced board still tally at its rough size?
Board-foot measure is based on the rough green dimensions before drying and surfacing. A 4/4 board planed to 13/16 inch still contains and is priced for the original 1 inch of rough thickness, which is the industry convention for hardwood.
How much waste should I add to a lumber order?
For clear-cutting hardwood around knots, checks, and end splits, 10-20% extra is a common planning allowance. Lower grades and projects with long clear parts need more; a rough default of 10% works for select and better stock.