Board Foot Calculator
Calculate board feet from the thickness, width and length of lumber, for one board or a whole order, and estimate the cost at a price per board foot.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Total board feet
- 40 bd ft
- 10 pieces of 1 in x 6 in x 8 ft
- Board feet per piece
- 4 bd ft
- 576 cubic inches
- Total length
- 80 ft
Board Foot formula
Board feet per piece = Thickness (in) x Width (in) x Length (ft) / 12
Total board feet = Board feet per piece x Number of pieces
Cost = Total board feet x Price per board footWorked example
Six pieces of 2 x 10 lumber 12 ft long, priced by the board foot at $4.00: 2 x 10 x 12 / 12 = 20 board feet each, so 120 board feet total and a cost of $480. If the yard measures actual dimensions instead (1.5 x 9.25 in), the same boards are 13.9 board feet each.
Quick reference
| Nominal size | Board feet per 8 ft piece |
|---|---|
| 1 x 4 | 2.67 |
| 1 x 6 | 4.00 |
| 1 x 8 | 5.33 |
| 1 x 12 | 8.00 |
| 2 x 4 | 5.33 |
| 2 x 6 | 8.00 |
| 2 x 8 | 10.67 |
| 2 x 12 | 16.00 |
How to calculate board feet
A board foot is a volume, not a length: 12 x 12 x 1 inches. Multiply thickness and width in inches by length in feet and divide by 12. If all three dimensions are in inches, divide by 144 instead. Anything thinner than 1 in is tallied as 4/4; there is no 3/4 in board foot at a hardwood yard.
For hardwood, use the nominal (rough-sawn) thickness even if the board has been planed. A 4/4 board surfaced to 13/16 in is still sold as 1 in thick. Width is measured at the narrowest point of the board, and length is rounded down to the nearest foot at most yards. The tally sheet lists every board the yard counted; check it against your own count before you pay.
Board feet vs linear feet
Construction lumber (2x4, 2x6) is priced per piece because the sizes are standard. Hardwood comes in random widths and lengths, 4 to 12 in wide and 6 to 12 ft long, so it is priced per board foot. A big box sells S4S oak and poplar by the linear foot at typically 2 to 3 times a dealer's rough price per board foot. A 1x6 is half a board foot per foot, so convert before comparing.
Grade sets the yield. FAS is 83 percent clear on the poor face in long cuttings. #1 Common is 67 percent clear in cuttings down to 3 in by 3 ft and costs 30 to 40 percent less. For cabinet parts under 3 ft, #1 Common is the buy. Convert the cut list to board feet and add 20 to 30 percent for FAS or 40 to 50 percent for #1 Common. That covers defects, straight-line ripping, grain matching and cutoffs.
What this calculator leaves out
Surfacing: S2S to 13/16 in on 4/4, S4S and a straight-line rip each typically add $0.25 to $0.50 per board foot (2026). Also the grade premium, minimum orders and delivery, and moisture. Interior work wants 6 to 8 percent, so sticker the lumber indoors for 1 to 2 weeks and meter it before milling. The result is the rough tally; after planing you own less wood than you paid for.
Mistakes that cost money
- Figuring 4/4 as a full inch: it surfaces to 13/16 in, so a 7/8 in part needs 5/4 stock at 25 percent more board feet.
- Buying FAS for parts under 3 ft: #1 Common yields the same short clear cuttings at 30 to 40 percent less per board foot.
- Comparing a big-box linear-foot price to a dealer's board-foot price: an S4S 1x6 is half a board foot per foot, so multiply by 2.
- Ordering the cut-list total with no allowance: random widths, rips, checks and knots turn 30 board feet of parts into a 40 board foot order.
- Surfacing left off the quote: S2S and a straight-line rip typically add $0.25 to $0.50 per board foot at the dealer (2026).
- Milling lumber straight off the truck: sticker it indoors 1 to 2 weeks until it meters 6 to 8 percent, or joints open by spring.
Key facts
- One board foot is 144 cubic inches of wood: a piece 1 in thick, 12 in wide and 12 in long.
- Hardwood thickness is quoted in quarters of an inch: 4/4 is 1 in, 6/4 is 1.5 in, 8/4 is 2 in.
- A 2 x 4 that is 8 ft long is 5.33 board feet by nominal size, even though its actual size is 1.5 x 3.5 in.
- Hardwood lumber is sold rough by nominal thickness; surfacing removes about 1/4 in but you still pay for the rough size.
- 1,000 board feet is written as 1 MBF; large orders and sawmill prices are quoted per MBF.
Frequently asked questions
How many board feet are in a 2x4x8?
5.33 board feet using nominal dimensions (2 x 4 x 8 / 12). Using actual dimensions of 1.5 x 3.5 in it would be 3.5, but lumber is always figured at nominal size.
What grade of hardwood should I buy?
FAS (Firsts and Seconds) and Select are the clear grades, 83 percent clear on the poor face in long cuttings, for tabletops, long rails and anything that shows. #1 Common is 67 percent clear in cuttings as small as 3 in by 3 ft and typically costs 30 to 40 percent less. It yields the same parts for cabinet doors, face frames and drawer sides, so buy #1 Common unless a part is over 3 ft and shows.
What does 4/4 mean in hardwood?
Four quarters of an inch, or 1 in nominal thickness. 5/4 is 1.25 in, 6/4 is 1.5 in and 8/4 is 2 in. The fraction refers to the rough-sawn thickness before planing.
How do I convert board feet to cubic feet?
Divide by 12. One cubic foot of wood is 12 board feet.
Sources and references
- Forest Products Terminology fact sheet F-85 (Ohio State University Extension)
- Hardwood Lumber Grades, FNR-130 (Purdue Extension)
- NHLA Rules for the Measurement and Inspection of Hardwood and Cypress (National Hardwood Lumber Association)
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Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.