Calculating Board Feet

[Jason Solodow]

If my understanding is correct, a board foot is equal to 144 cubic inches of material. So a piece of 4/4 wood measuring 12" x 12" is one bd ft. Is this correct?

Thanks!

[Rod Sheridan]

That's correct..........Rod.

[Nissim Avrahami]

Have a look here
http://www.woodproductsonlineexpo.com/content.php/675/2117/wood_products_fbm.html

Regards
niki

[Gene Howe]

If my understanding is correct, a board foot is equal to 144 cubic inches of material. So a piece of 4/4 wood measuring 12" x 12" is one bd ft. Is this correct?

Thanks!

You are correct in your calc.s. But some lumber retailers will sell a 12"X12" by 3/4" as 1 bf. :mad:

[Gene E Miller]

Greetings & Salutations,

That is correct and the formula for any piece is:

(Thickness x Width x Length) / 144 = BF

All of the above are in inches.

Gene

[Brian Kent]

The thickness is the raw cut thickness before planing. 4/4 thickness is four fourths of an inch or 1 inch thick at the saw mill. Then it is dried and planed, and the result is usually 3/4" but it still counts as 1 inch.

[Steve Griffin]

It's usually much easier to use feet for the length. Most sellers of lumber round off the length to feet anyway.

Often a guy can even do the math in his head with this method.

Thickness (inches) x Width (inches) x Length (feet) /12 =BF

-Steve

[Chris Padilla]

Board feet is a volume measurement.

It's units are actually in-ft² (inches foot squared)*. Just remember that the thickness is always in inches which should be easy because no one ever quotes lumber thickness in anything but inches. They use this rather silly 4/4 or 5/4 or 12/4 nomenclature instead of saying 1, 1 1/4, or 3 inches thick.

The length is normally in feet so that one is easy to remember.

The width is the trickier one because that is normally in inches and not feet. That is why Steve's formula shows a /12 in it in order to convert the width in feet to the width in inches. (Personally, I think a bf should be redefined with the width calculated in inches but whatever....).

I think this deeper understanding of what a board foot is ought to give you some confidence in dealing with it from your lumber supplier.

Also, as others have pointed out, this is for ROUGH dimensions. FINISHED dimensions are always smaller...especially in regard to thickness. If you want FINISHED 4/4 lumber, you will get a thickness LESS THAN 4/4 (1"). Typically, it'll be 3/4". If you need a FINISHED 1" thickness, you will have to buy 5/4 lumber.



* - Note: This is NOT inches PER foot squared, which is in/ft² . It is inches times foot squared, or in-ft² . :)