Terminology explanation

[Eigenvector]

So I took a gander at a high-end wood retailer today at lunch and came across some stuff that I can't figure out. Some boards were sold as $x.yy per board foot and others were sold as $x.yy per square foot. Why the differences? It appeared as though the 1/2 boards were all sold square foot and the 4/4, 8/4, and 16/4 boards were sold board foot. What exactly is a board foot? I'm presuming that's what BF meant on the price - and none of the wood was dimensioned.

[Jim]

A board foot of 4/4 wood is 12 x 12 inches. A board foot of 8/4 wood is 6x6 inches, etc. Boards thinner than 4/4 are usually sold by the square foot if for no other reason that people don't realize how much it costs. To make a 1/2 inch thick board, people usually start with

4/4 and plane it down. The customer pays for the scrap.

Boards sold by the board foot need not be otherwise dimensioned.

And, hardwood is sold in random widths and random lengths. You pay plenty for the scap if you want specific widths and / or lengths. Jim

[DJ Delorie]

A board foot is a VOLUME of 144 cubic inches of ROUGH wood. Picture a

1' by 1' by 1" slab of rough cut wood; that's a board foot. In fact, go make one, write "BF" on it, and hang it in your shop. Make a 2"x6"x12" one to go next to it, and a 1"x6"x24" one too. They're all a board foot.

A 1 foot cube of wood (1x1x1) is thus 12 board feet.

Some things are easier to sell by the linear foot, like mouldings.

Some things are easier to sell by the square foot, like plywood.

With surfaced wood, you have to figure it based on the original rough size. Thus, a 1.5 x 3.5 x 8' board is 2 x 4 x (8*12) / 144 = 5.33 bf.

What I tend to do is figure out how long a board has to be to be a board foot, then scale. Example: a 2x8 rough is 16 sq in, or 4/3 of a sq ft. So a board foot is 3/4 of a foot of that board, or a 2x8 9" long. A 9 foot length is thus 12bf.

A 2x6 or 1x12 is 1 bf per foot of length.

A 1x6 or 2x3 is 1 bf per two feet of length.

A 1x4 is 1 bf per 3 feet of length.

Etc.

[Edwin Pawlowski]

Jim was typing faster than he was thinking. 12 x 12 x 1 is a board foot So is 6 x 12 x 2 a board foot. It is probably easier to think in terms of

144 cubic inches. Keep in mind, a board that is sitting on the shelf that measures 12 x 12 x 3/4 was planed down so it will still be charged as a board foot.

Just to confuse you more, some of the big box stores sell their wood by the lineal foot. That way, a 6" wide board will cost roughly double per foot compared to a 3" wide board.

[James "Cubby" Culbertson]

BF is LxWxH in inches divided by 144. Hardwood is often sold in the quarters system where 4/4=1" thick, 6/4= 1.5" thick, etc... So as an example, a 4/4 board that measures 6" wide and 72" long would be:

1" (H) X 6" (W) X 72" = 432 cubic inches/144 cubic inches = 3BF. Make sense?

[George]

What makes sense is to use the built-in terminology and screw the 144 business.

My pickup has 4 ft of 102" (8ft) boards per tier. Makes 32 my base. 4/4 is the 32, 5/4 is 160(5x32)/4 = 40 . That way you can do your calcs in your head if you're over forty, with a pencil if you're over thirty, or trust the pimple-factory and his calculator if you're younger ....

[Thom]

I use a slight variation of the calculation -- for me it is easier to do in my head while shopping for the lumber I want or need. A x B x C

---------- 12

Where A = thickness in inches B = width in inches C = length in feet

So for example I have a 4/4 piece of oak that is 6" wide and 8 feet long.

1 x 6 x 8

--------- = 4BF 12

Thom

[mac davis]

And then there's places that price by the POUND! I was comparing pricing cocobolo and jarrah for a clients goblets and the CB was available in 4" x 4" x 12" pieces for $40.. Ok, that's the kind of stuff I can understand... Maybe even calling it 16/16 or something.. OTOH, the jarrah was $6 a pound??? I emailed them asking what the approximate weight of a 4x4x12" chunk of jarrah was and got "about 8 or 10 pounds" as a reply.. hard to give a client a bid based on that pricing..lol

mac

Please remove splinters before emailing

[mac davis]

Yeah, that's the way I learned it, from some book in the distant past...

Wouldn't it work out the same if you used an inch per foot on the length and didn't have to divide the sum by 12? (Yeah, I flunked math in HS)

mac

Please remove splinters before emailing

[Jim]

I wrote that post while half asleep. Mathematics in my head is not my strong suit anymore. Jim

[Charlie M. 1958]

I knew that you knew better, but I didn't want the guy who was shaky on board footage to be scratching his head too long. :-)

[James "Cubby" Culbertson]

Yeah, there are all sorts of ways to figure it given there are feet and inches involved. I personally found a tape measure that had the BF scale on the back of it similar to what the lumber yard uses to measure BF and use that although for a board or two, I usually just do it in my head. Cheers, cc