Board Foot Calculator
Add every board to one running tally and get total board feet, cost, and how much to order with waste. Free, instant, and it saves your list in this browser.
| Qty | Thickness | Width | Length | Board feet | |
|---|---|---|---|---|---|
| 40 | |||||
| 21.33 |
Board feet use the formula thickness x width x length in inches, divided by 144. Lumber is normally figured at nominal size (a 2x4 counts as 2 by 4). Hardwood thickness is often given in quarters: 4/4 = 1", 5/4 = 1.25", 8/4 = 2". Your tally saves in this browser.
What a board foot is
A board foot is a unit of volume for lumber. One board foot equals 144 cubic inches, which is a piece one inch thick, twelve inches wide, and one foot long. It is not a measure of length or surface area, so you always need three numbers to find it: thickness, width, and length.
The formula is simple:
board feet = (thickness in x width in x length in) / 144
If your length is already in feet, you can skip a step:
board feet = (thickness in x width in x length ft) / 12
Why the tally matters
Nobody buys one board at a time. A real project is a cut list: a few 8 foot 1x6s, some 2x4s, a couple of wide boards for a top. Most calculators make you do one board, write down the answer, clear the form, and start over. This one keeps every board in a single table and adds them up as you go, so the number at the bottom is what you actually take to the lumberyard.
Add a price per board foot and it estimates the cost. Add a waste percentage and it pads the order for cutoffs, defects, and mistakes. Most woodworkers add 10 to 20 percent depending on how much ripping and crosscutting the design needs.
What bd ft, BF, and FBM mean
Lumber gets abbreviated a dozen ways, and the abbreviations are more common at the yard than the full words:
- BF or bd ft or bdft all mean board feet
- board foot is one unit, board feet is more than one
- FBM means feet board measure, the older term for the same thing
- MBF means thousand board feet, how mills quote bulk volume
They all refer to the same unit, so whichever one is on the price tag, the calculator above handles it. Board feet is a volume, so it always needs three numbers: thickness, width, and length.
Working out cost
The calculator also does cost, which is usually the real question. Yards quote hardwood as dollars per board foot, so once you know your total volume the price is one multiplication.
Enter a price per board foot next to your boards and the tally shows running cost alongside running volume. Add a waste percentage and it prices the padded order instead of the bare cut list, which is the number you actually hand over.
Current going rates by species are on the lumber prices page. Pine and poplar run a few dollars a board foot, domestic hardwoods like oak and maple sit higher, and figured or imported stock goes up from there.
What 1, 20, and 200 board feet actually look like
The unit is hard to picture until you tie it to real boards:
| Volume | In real lumber |
|---|---|
| 1 board foot | A 1x12 cut one foot long, or a 1x6 two feet long |
| 4 board feet | One 1x6 at 8 feet |
| 5.33 board feet | One 2x4 at 8 feet |
| 20 board feet | Five 1x6x8s |
| 200 board feet | Fifty 1x6x8s, or about thirty-eight 2x4x8s |
The 2x4 questions come up constantly, so plainly: a 2x4x8 is 5.33 board feet, a 2x4x10 is 6.67, and a 2x4x12 is 8. The board foot chart has every common size worked out if you would rather read it off a table than type it in.
Board feet, linear feet, and square feet
Three different units, and mixing them up is the most common lumber math mistake. Board feet is volume, linear feet is plain length, and square feet is face area, which is why a linear foot price and a board foot price are never comparable numbers.
The board foot vs linear foot page works through the conversion in both directions, including the one inch nominal shortcut and how it changes on thicker stock.
When you are measuring something other than a board
- Standing timber or sawlogs use log rules rather than the board formula. The log scale calculator runs Doyle, Scribner, and International.
- Shipping or a floor load needs weight, not volume. The lumber weight calculator handles that by species and moisture content.
- If you want the reasoning rather than the arithmetic, what is a board foot and how to calculate board feet cover the definition and the method.
Nominal vs actual size
Lumber is figured at nominal size, not the size you measure with a tape. A construction 2x4 is really about 1.5 by 3.5 inches once it is planed, but it is bought and priced as a 2x4. Hardwood is a bit different: rough boards are close to their stated thickness and are sold in quarters, where 4/4 is one inch, 5/4 is one and a quarter, and 8/4 is two inches. Enter the nominal numbers and the tally matches what the yard charges you for.
Worked example
Say you need ten 1x6 boards at 8 feet and four 2x4s at 8 feet.
- Ten 1x6x8: 1 x 6 x 8 / 12 = 4 board feet each, so 40 board feet
- Four 2x4x8: 2 x 4 x 8 / 12 = 5.33 board feet each, so 21.33 board feet
- Total: 61.33 board feet
At 5 dollars per board foot with 15 percent waste, that is about 70.5 board feet to order and roughly 353 dollars of material. The calculator above does all of that as you type, and it saves your list in this browser so it is still there when you come back.
Frequently asked questions
- How do I calculate board feet?
- Multiply thickness in inches by width in inches by length in inches, then divide by 144. If the length is in feet, multiply thickness by width by length and divide by 12 instead. The calculator on this page does it for a whole list of boards at once.
- Is a board foot the same as a linear foot?
- No. A linear foot only measures length. A board foot measures volume, so it also depends on thickness and width. A 1x6 gives half a board foot per linear foot, while a 2x12 gives two board feet per linear foot.
- Do I use nominal or actual size?
- Use nominal size, the size the lumber is sold as. A 2x4 is figured as 2 by 4 even though it measures about 1.5 by 3.5 after planing, because that is how the lumberyard prices it.
- How much waste should I add?
- Most projects add 10 to 20 percent. Add more for short parts, a lot of ripping, rough or defect-prone stock, or if you are new to a cut and expect a few mistakes.
- Does this work for metric sizes?
- Yes. Switch the thickness and width unit to millimeters or centimeters and the length unit to meters. The result is still in board feet, the standard lumber unit in the US and Canada.
- What does bd ft mean?
- Bd ft is shorthand for board feet, the volume unit lumber is sold in. You will also see BF, bdft, and FBM (feet board measure) used for exactly the same thing. One board foot is 144 cubic inches.
- How many board feet are in a 2x4x8?
- 5.33 board feet. The math is 2 x 4 x 8 / 12. A 2x4x10 is 6.67 board feet and a 2x4x12 is 8. Use the nominal 2x4 numbers, not the planed 1.5 by 3.5 measurement, because that is how the yard prices it.
- How do I work out the cost per board foot?
- Divide the total price by the total board feet. Going the other way, enter your price per board foot in the calculator above and it multiplies out the running cost as you add boards. Adding a waste percentage prices the order you actually place rather than the bare cut list.
- Is a board foot the same as a square foot?
- Only for one inch nominal stock, where the two happen to match: a 1x6x8 is 4 board feet and 4 square feet of face. For thicker material they diverge, so a 2x4x8 is 5.33 board feet but only 2.67 square feet of face. Board feet measures volume, square feet measures area.
- What is MBF?
- MBF means thousand board feet, using the Roman M for a thousand. Mills and wholesalers quote bulk lumber in dollars per MBF. To compare against a retail per board foot price, divide the MBF price by 1,000.