Board Foot Calculator — Hardwood by Volume
Hardwood is not sold by the foot or the piece — it is sold by volume, in board feet. Enter the dimensions of one board and how many you want, and this gives you the board feet and what they will cost.
Take this list to the store
We'll email the quantities above, what you typed in, and a link that reopens this calculator already filled in — so you can adjust it on your phone in the aisle.
How to work it out
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Measure the actual size
Thickness and width in inches, length in feet. Use what the board really measures, not what it is called. A board sold as 1 × 6 pine is 3/4 × 5 1/2 in., and using the nominal numbers will overstate the volume by nearly a third.
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Multiply and divide by twelve
Thickness times width times length, divided by 12. That is the whole formula. It comes out in twelfths because length is in feet while the other two are in inches — a board foot is 144 cubic inches, and 144 ÷ 12 = 12.
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Round the way the yard rounds
Most hardwood dealers round each board up to the next quarter, and some round width up to the next whole inch. Ask. On a big order the difference between their arithmetic and yours is real money.
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Buy more than the project needs
Hardwood has defects, and you will cut around them. Twenty to thirty per cent over your finished requirement is normal for rough lumber, less for surfaced. This calculator gives you what the boards contain, not what your project needs.
Board feet in common sizes
Using actual dimensions.
| Size | 6 ft | 8 ft | 10 ft | 12 ft |
|---|---|---|---|---|
| 1 × 4 in. | 2.00 | 2.67 | 3.33 | 4.00 |
| 1 × 6 in. | 3.00 | 4.00 | 5.00 | 6.00 |
| 1 × 8 in. | 4.00 | 5.33 | 6.67 | 8.00 |
| 1 × 12 in. | 6.00 | 8.00 | 10.00 | 12.00 |
| 2 × 6 in. | 6.00 | 8.00 | 10.00 | 12.00 |
| 2 × 8 in. | 8.00 | 10.67 | 13.33 | 16.00 |
| 2 × 12 in. | 12.00 | 16.00 | 20.00 | 24.00 |
A 1 × 12 and a 2 × 6 hold the same volume. Board feet measure wood, not shape.
What the quarters mean
Rough hardwood thickness is quoted in quarter-inches.
| Quoted | Rough thickness | Surfaced two sides | Typical use |
|---|---|---|---|
| 4/4 | 1 in. | 13/16 in. | Boxes, drawer sides, panels |
| 5/4 | 1 1/4 in. | 1 1/16 in. | Stair treads, thick tops |
| 6/4 | 1 1/2 in. | 1 5/16 in. | Table aprons, sturdy shelves |
| 8/4 | 2 in. | 1 3/4 in. | Legs, thick tops, turning stock |
| 12/4 | 3 in. | 2 3/4 in. | Heavy legs, carving blanks |
You are charged for the rough thickness even when you buy it surfaced. The shavings are on your bill.
How do you calculate board feet?
Thickness in inches times width in inches times length in feet, all divided by twelve. An 8 ft board that is 1 inch thick and 6 inches wide is (1 × 6 × 8) ÷ 12 = 4 board feet.
If you have the length in inches instead of feet, divide by 144 rather than 12. Both are the same sum — a board foot is 144 cubic inches of wood, which is one inch thick, a foot wide and a foot long.
Why hardwood is sold this way
Softwood comes out of the mill in standard sizes, so a yard can sell you a 2 × 4 by the piece. Hardwood does not. It is cut to get the most usable wood out of each log, so boards arrive in random widths and lengths — one 7 1/4 inches wide, the next 9 3/4.
You cannot price that by the piece, so it is priced by volume. Board feet is the unit that lets a 6 inch board and an 11 inch board be compared fairly.
Nominal versus actual, and why it costs you
A 2 × 4 is 1 1/2 × 3 1/2 in. A 1 × 6 is 3/4 × 5 1/2. Those names describe the board before it was dried and planed, and nobody has sold wood at its nominal size in a century.
For board feet on softwood this matters enormously: calculate a 1 × 6 × 8 ft at its nominal size and you get 4 board feet, but the actual board holds 2.75. For rough hardwood you measure what is in front of you, which is why this calculator asks for real dimensions rather than a size name.
Quarters, and paying for shavings
Rough hardwood thickness is quoted in quarters of an inch. 4/4 ("four quarter") is a nominal one inch, 8/4 is two. When it is surfaced on both faces, 4/4 comes out at about 13/16 in. — but you are still charged for the full inch.
That is not a swindle, it is just how it is priced: the mill cut an inch of wood and the planer turned some of it into shavings. Factor it in when you are comparing a rough price against a surfaced one.
How much to buy over what you need
Work out the board feet in your finished pieces, then add 20 to 30 per cent for rough lumber. Hardwood comes with knots, checks, wane and bow, and you cut around all of it. Wide boards and long boards make it worse, because a defect anywhere ruins more of the piece.
For surfaced, straight-line-ripped stock, 15 per cent is usually enough. For anything where grain has to match across a panel, buy it all at once from one lift — you will not match it on a second trip.
How this is worked out
No black box — here is the arithmetic the calculator runs, so you can check it against your own numbers.
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board feet = (thickness in. × width in. × length ft) ÷ 12A board foot is 144 cubic inches. Length in feet puts the divisor at 12. -
board feet = (thickness in. × width in. × length in.) ÷ 144The same sum with every dimension in inches. -
total = board feet per piece × number of piecesVolume adds up the way you would expect. -
cost = total board feet × price per board footHardwood is priced by volume, not by the piece or the running foot. -
cubic feet = board feet ÷ 12Twelve board feet make a cubic foot.
Common questions
What is a board foot?
A piece of wood one inch thick, twelve inches wide and twelve inches long — 144 cubic inches. It is a measure of volume, so any shape holding that much wood is one board foot.
How many board feet in a 2 × 4?
Depends on the length, and on whether you use nominal or actual size. An 8 ft 2 × 4 at its nominal size is 5.33 bd ft; at its real 1 1/2 × 3 1/2 in. it is 3.5. Softwood is normally sold by the piece anyway, so the question rarely comes up outside of pricing comparisons.
Is a board foot the same as a linear foot?
No, and confusing them is the expensive mistake. A linear foot is a foot of length whatever the board is. A board foot is a volume. Ten linear feet of 1 × 4 is 3.3 board feet; ten linear feet of 1 × 12 is ten.
What does 4/4 mean?
Four quarters of an inch — a nominal one inch thick, rough. 5/4 is 1 1/4 in., 8/4 is 2 in. and so on. It is how rough hardwood thickness is quoted, and you pay for the rough figure even after surfacing takes it down.
Do I use nominal or actual dimensions?
Actual, always, for hardwood — measure the board. For rough stock that means the narrowest point of the width. Yards often round widths up to the next inch when they tally, so ask how they measure before you argue about the total.
How much does a board foot of oak weigh?
About 3.5 to 4 lb for red oak at normal indoor moisture content. Hard maple is similar, walnut a little under 3, and white pine closer to 2. Useful when you are working out whether it is going in the car.
How many board feet do I need for a table?
Work out the volume of the finished parts, then add 25 to 30 per cent for defects and cutting. A typical 6 ft dining table in 8/4 stock lands somewhere around 40 to 60 board feet depending on the base. Buy it in one go so the color matches.
Why is the divisor 12 and not 144?
Because length is in feet while thickness and width are in inches. One foot is twelve inches, so the 144 has already been divided once. Put all three dimensions in inches and you divide by 144 instead.
Where these figures come from
Every figure below is traceable. How we check the numbers explains how they are verified, and the coverage reference collects them all in one place.
- National Hardwood Lumber Association — grading rules and board foot measure
- US Forest Products Laboratory, Wood Handbook — lumber measurement conventions
- American Softwood Lumber Standard PS 20 — nominal and actual dimensions
Think a number here is wrong? Tell us — we check every report, correct the page, and date the change. Last checked September 15, 2026.