Quick way to find board feet - Woodworking Talk - Woodworkers Forum
Old 09-16-2020, 09:54 AM Thread Starter
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Quick way to find board feet

Sometimes you may need to know just how many board feet a particular board is or how many you'll need . Not every board is going to be 1" thick by 12" wide. Suppose it's 7 1/2"x 3/4" x 5 feet long.. Quite a problem, huh?
No. It's really easy. Multiply board length in feet, 5 in this case by 7.5, width then divide by 12. This doesn't help with thickness, but for nominal measurements it's close enough since with thickness they just round up or down to the nearest inch. That 3/4" is represented by 1". This makes things confusing especially if the thickness is less than 1/2". You really can't have a board 0" thick. It's nothing at this point.
Someone explain that one, eh? I can't, but anything over a 1/2" is easy peasy.. Actually I can, but I just don't have the words to explain it.. 1/4" x 7.5 x 5 feet.. hmmmm.. lol

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Old 09-16-2020, 10:55 AM
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The measurement of thickness is considered to have started as a 4/4 board in the rough, so if the dimensioned board is 3/4" somebody has to pay for the extra 1/4" that was planed off; that's the customer. That's why thickness is considered to be 1" (4/4). If the dimensioned board is 1/2" but was planed down from a 4/4 board then you would still use 1" for calculations, unless you find a sawmill or supplier willing to throw money away.

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Old 09-16-2020, 11:41 AM
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I measure inches x inches x inches (height x width x thickness). Multiply them together and divide by 144. The result is board-feet.

The other important "trick" is to remember to increase the thickness appropriately to compensate for machining losses. If the board is 3/4 inch thick, then treat it as 1 inch thick in your calculation. If 1 inch thick, treat it as 1-1/4. It depends on how the board was surfaced before you bought it. If you aren't sure, add 1/4 inch and you will be close.
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Old 09-17-2020, 12:04 AM
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It all depends upon WHERE you are doing the calculation. If you are in math class, your method is correct. If you are in the lumber yard the calculation would be:

2/3 x 5 = 3-1/3 which would be rounded up to 3-1/2 if you were a good customer. (8 inches is 2/3 of a foot) If you are just that guy from the next county trying to score some cheap timber it would be 4. Some, but not all, lumber yards will allow the fractional board feet to accumulate and add to the total rather than rounding up each piece of timber.

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Old 09-18-2020, 07:04 AM
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You can use the Essex board feet table on a framing square for “pretty close” estimates.

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