Per board
4.00 bf
Board Foot Calculator
Board feet for hardwood lumber, from thickness, width and length — including the quarter sizes the yard quotes in.
Hardwood is quoted in quarters of an inch. 4/4 is one inch.
Use the rough thickness, not the planed one.
Same size each.
4.00 board feet
One board of 1 in × 6 in × 8 ft.
Cubic feet
0.33
Estimated cost
—
Linear feet
8.0
Yards charge by the rough size, not the planed size. If you buy 4/4
lumber surfaced down to 13/16 in, you are still billed for the full inch. Use the
nominal thickness the yard quotes — that is what ends up on the invoice.
How this is worked out
A board foot is a volume: one square foot of lumber, one inch thick. That is 144 cubic inches.
With everything in inches:
(thickness × width × length) ÷ 144 = board feet
With the length in feet, which is how boards are usually sold:
(thickness in × width in × length ft) ÷ 12 = board feet
Worked example — one 4/4 board, 6 in wide, 8 ft long
- Thickness 4/4 is
1 inch - In inches:
1 × 6 × 96 = 576 cubic inches 576 ÷ 144 = 4 board feet- Or the short way:
1 × 6 × 8 ÷ 12 = 4 board feet - At $8.50 a board foot:
4 × 8.50 = $34.00
Quarter sizes
Hardwood yards quote thickness in quarters of an inch. It looks like a fraction but it is just the number of quarter-inches.
| Quoted | Thickness | Common use |
|---|---|---|
| 4/4 | 1 in | Most furniture parts, shelving |
| 5/4 | 1¼ in | Stair treads, thick tops |
| 6/4 | 1½ in | Table legs, heavy frames |
| 8/4 | 2 in | Legs, thick slabs |
| 12/4 | 3 in | Turning stock, posts |
| 16/4 | 4 in | Heavy posts and beams |
Questions people ask
Is a board foot the same as a linear foot?
No, and mixing them up is the usual mistake. A linear foot is just length — it says nothing about how wide or thick the board is. A board foot is volume. Two boards can both be 8 linear feet and be very different amounts of wood.
Why doesn't a 2x4 give the answer I expect?
Because softwood is sold by nominal size. A "2x4" actually measures about 1½ by 3½ inches. Construction lumber is normally priced per piece or per linear foot anyway, not per board foot. Board feet are a hardwood thing.
How much extra should I buy?
For rough-sawn hardwood, add 20 to 30%. You lose wood to jointing, planing, ripping out defects and snipe at the ends, and boards are rarely the full width they are sold as. For surfaced, straight stock, 15% is usually enough.
How do I measure a board that isn't a neat rectangle?
Measure the width at the narrowest point if you need the usable amount, or take an average width if you are checking a yard's tally. Yards normally measure to the nearest inch of width and round down on part-inches, which is why their total can come out below yours.
What does a board foot weigh?
It depends entirely on the species and how dry it is. Kiln-dried oak is roughly 3.5 to 4 lb a board foot, poplar nearer 2.5, and green lumber is far heavier. Ask the yard if you are working out a load.