Board Foot Calculator: Cut List, Waste & Cost
Add every board on your cut list and this calculator returns the total board feet, the footage to order once you allow for waste, and the cost. Enter thickness and width in inches and length in feet (the way rough lumber is usually described), or switch to millimetres. Results update as you type.
What a board foot actually is
A board foot is a unit of volume, not length - it's the amount of wood in a plank one foot long, one foot wide, and one inch thick (144 cubic inches). Hardwood lumberyards price rough stock by the board foot, so a wider or thicker board of the same length costs more, and that's exactly what trips up people used to buying dimensional lumber by the linear foot.
That's the whole reason this tool exists: a linear foot just measures length, but a board foot folds thickness and width into the price. Two 8-foot boards can be the same linear length and yet be very different quantities of wood - and money - once you account for how thick and wide they are.
How to calculate board feet (the formula)
If you'd rather calculate by hand - or check the tool - here's the exact conversion.
With length in feet (thickness and width in inches):
Board feet = (Thickness in × Width in × Length ft) ÷ 12
With all three dimensions in inches:
Board feet = (Thickness in × Width in × Length in) ÷ 144
(A board foot is 144 cubic inches - 12 × 12 × 1 - which is where both divisors come from.)
To estimate cost:
Total cost = Total board feet × Price per board foot
Quarter measurements like 4/4, 5/4, 6/4, 8/4 are just how the trade writes rough thickness in quarter-inches: 4/4 = 1", 5/4 = 1.25", 8/4 = 2". Board footage is figured on the rough (pre-surfaced) thickness, so a 4/4 board is billed as a full inch even after it's planed down to 3/4".
Board feet in common lumber sizes
Dimensional lumber is figured on its nominal size - a 2x4 counts as 2" x 4" even though it measures about 1.5" x 3.5" - because that's how yards quote it. Board feet per piece:
| Nominal size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1x4 | 2.67 | 3.33 | 4 | 5.33 |
| 1x6 | 4 | 5 | 6 | 8 |
| 1x8 | 5.33 | 6.67 | 8 | 10.67 |
| 1x12 | 8 | 10 | 12 | 16 |
| 2x4 | 5.33 | 6.67 | 8 | 10.67 |
| 2x6 | 8 | 10 | 12 | 16 |
| 2x8 | 10.67 | 13.33 | 16 | 21.33 |
| 2x10 | 13.33 | 16.67 | 20 | 26.67 |
| 2x12 | 16 | 20 | 24 | 32 |
| 4x4 | 10.67 | 13.33 | 16 | 21.33 |
So a 2x4x8 is 5.33 board feet, a 2x6x8 is 8, and a 4x4x8 is 10.67. Rough hardwood is different: it's sold by its rough quarter thickness (4/4, 5/4, 8/4) and random widths, so measure each board and use the cut list above.
Worked example
Say you're pricing a board 1 inch thick, 6 inches wide, and 8 feet long:
Board feet = (1 × 6 × 8) ÷ 12 = 48 ÷ 12 = 4 bd ft
That single board is 4 board feet. If you need ten of them, that's 40 board feet total. At a quoted rate of $5 per board foot:
Total cost = 40 × $5 = $200
Those are the same numbers the calculator above returns when you plug them in (one row, quantity 10, $5, waste 0%).
Who this is for
If you work wood professionally, board-foot math is second nature. This tool is really for beginner woodworkers and DIY homeowners who've just gotten a hardwood quote priced "per board foot" and need to turn a cut list into a real budget - before placing the order, measure the thickness, width, and length of each piece, run it through the calculator, and you'll know both the footage to order and the ballpark cost.
Planning a build? Pair this with our wood CFT calculator and lumber calculator for the other units you'll run into, and once your stock is home, square and flatten it with the best cordless planers.
Frequently Asked Questions
How many board feet are in a square foot?
There's no single answer - it depends on thickness. A square foot of 1-inch (4/4) stock is one board foot; a square foot of 2-inch (8/4) stock is two board feet. Board feet measure volume, square feet measure surface area, so the conversion always needs the thickness.
Is a board foot the same as a linear foot?
No. A linear (running) foot only measures length, ignoring width and thickness - that's how dimensional lumber and moldings are often sold. A board foot measures volume, which is how rough hardwood is priced. The calculator above converts your dimensions into board feet for you.
What does 4/4 mean in lumber?
It's rough thickness in quarter-inches: 4/4 is 1 inch, 5/4 is 1¼ inch, 8/4 is 2 inches. Yards bill board footage on this rough thickness even though surfacing removes about ¼ inch, so 4/4 stock planed to ¾ inch is still charged as a full inch.
Should I add extra for waste?
Yes. Set the waste field above: roughly 15-20% is typical for rough hardwood, to cover defects, cutoffs, and grain matching, since rough boards are rarely usable end to end. Surfaced, clear stock needs less.
How do I calculate board feet in metric?
Switch the calculator to millimetres and enter each board in mm. It converts using 1 inch = 25.4 mm and 1 board foot = 144 cubic inches, which works out to about 0.00236 cubic metres per board foot (roughly 424 board feet per cubic metre). Both figures are shown.