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Thread: How to calculate board feet for project?

  1. #1
    Join Date
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    How to calculate board feet for project?

    I've recently set up a shop in my garage and turned out some small projects, mostly jewelry boxes, humidors, kitchen cabinet full extension drawers, etc. I'm looking at something a bit more ambitious; a set of bedroom furniture this winter. I'm still looking for plans, but I've noticed most plans give a parts list, but don't really give a good idea of how much rough cut lumber I need to pick out. I'm looking at building a nightstand, tall dresser, and a low 4-6 drawer dresser. Any very general ideas regarding how many board feet each of these projects might require? Thanks!

  2. #2
    http://cutlistplus.com/
    This is what I use. Just input the cutlist and the BF will be computed. Plywood layout too
    Hello, My name is John and I am a toolaholic

  3. #3
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    If you have a cut list you can calculate the BF needed for a project.
    Multiply width x length x thickness (all in inches) and divide by 144.
    Example: 8" wide board, 8' long, 1"thick
    8 x 96 x 1= 768 / 144 = 5.333 BF
    Don't forget to add in a waste factor. I usually add about 30%.

  4. #4

    On larger projects,

    I usually add about 20% extra. If you plan properly before you cut, you can maximize your wood by looking for smaller cut-offs to become drawer faces etc. In order to maximize I also get the longest / widest boards I can find.
    Sorry for the edit, but it just occurred to me that maybe you 'literally' dont know how to calculate 'board feet'.
    A board foot ideally is 12" x12" x1" or a square foot at 1" thick. You can calculate you total square inches required and divide that by 144 to get board feet. Then multiply by 1.2 and that will give you your new total required including the 20% spare.

    Tony B
    Last edited by Tony Bilello; 09-24-2008 at 9:17 AM.

  5. #5
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    I normally add 40 to 50%.

    I know it looks high, however consider that if I take 4/4 down to 3/4 planed dimension, I've already blown 25% through the cyclone.

    Add some more for grain selection, checks and shakes and you can easilly add another 5 to 15% to the project.

    regards, Rod.

  6. #6

    Rod

    In your statement "consider that if I take 4/4 down to 3/4 planed dimension, I've already blown 25% through the cyclone." That is not quite right. If you bought the 3/4" stock, you are still paying for 1", so you haven't 'lost' anything. Other than anything thicker than 1", you can just think of a board foot as a 'square foot'. Most places I go to will charge you for a full 1" even when you buy 1/2" stock.
    If you buy stock planed to 1", you will be paying for 5/4 stock or 25% more money for the same square footage.

    Tony B

  7. #7
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    Hi Tony, I purchase lumber rough, by the board foot.

    It is a volume measurement, so when I buy 4/4 it really is 1" thick, rough, and I've paid by the cubic foot (board foot) for it.

    When I need a piece of 3/4 material, I buy 4/4 rough, and 25% of it (at least) is in the cyclone after jointing and planing.

    If I want a piece with finished dimensions of 3/4" X 11.5" X 11.5", it is .69 board feet, yet it has come from a piece of rough stock that is 1" X 12" X12", or 1.0 board feet. So yes, I need to purchase 25% to 30% more material than I need from the cutting list.

    If your cutting list is in finished dimension form (which every cutting list I've seen is) then once you calculate your finished dimension board feet, you will need to add aproximately 25 to 30% just for jointing and planing. Stock selection will add another 5 to 15% at least.

    Regards, Rod.

  8. #8
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    Yep, someone nailed it; I didn't know how easy it was to calculate BF from the cutlist. A couple minutes with Excel will give me my answer. Thanks!

  9. #9

    I have a spreadsheet

    that my brother sent me a couple of years ago that has not only BF calcs but Shellac, miters, Drill sizes and a bunch of other stuff. The file name I have is 504. It is not for commercial use but still pretty cool. Anybody know where this can be downloaded. If not I can email to anyone that wants it.

  10. #10
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    Quote Originally Posted by John Holder View Post
    that my brother sent me a couple of years ago that has not only BF calcs but Shellac, miters, Drill sizes and a bunch of other stuff. The file name I have is 504. It is not for commercial use but still pretty cool. Anybody know where this can be downloaded. If not I can email to anyone that wants it.
    I'd like to take a look! Can you email it to mattroth54 at gmail dot com?

    Thanks!

  11. #11
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    You can punch a bunch of numbers into a spread sheet and churn out another number. That tells you how much lumber is in the finished product. What's tough is walking into a lumber yard and picking boards that agree with the spread sheet. Figuring the waste factor and minimizing it its the hard part and no computer is going to do that for you.

    You didn't mention species. Pattern grade mahogany? For me, add a 10% waste factor maximum. You couldn't build a bird house with the drops. Walnut? Add 40%, maybe more if things don't go well. Sap, sap, sap. Jatoba? There are lots of checks and cracks that seem to appear only in the bright light of my shop but never in the dim light of the lumber yard! White oak? If color matters you'll need to carry each board out into the day light, because they all seem to match under fluorescent light. Cherry? Good luck. Each species is a new adventure in beauty and frustration.

    My point is not to be a sarcastic mule here, but that it is a little trickier than developing some number plus a waste factor. Lots of variables. I rarely develop a BF number but always go to the lumber yard armed with a cut list, sometimes drawings too. I buy 4/4 for 3/4", sometimes if the stock seems flat enough and I'm feeling brave I'll call 4/4 7/8" finished. 5/4" up to 1 1/16", and so on. Rod's argument about adding 25% waste for the planer makes sense if you rely on a spread sheet and final dimensions, but I don't ever figure things that way. If a part calls for 3/4", I translate that to 1" rough in my head and calculations. By experience I know what I can expect to get out of an actual board best case scenario, and I remember to add 1/8" for each kerf plus as much as 1/4" for jointing.

    I mark up boards in the yard with a crayon or chalk, look for my parts in the stock, try to buy lengths and widths that fit my situation. I make a pile and check off parts as they are accounted for in my pile. Sometimes I change my design in the yard to suit what I find, other times that is not possible with in the scope of a project. Sometimes you need a 4/4 X 6" X 9' for a table top (say 18"X36") , but you get to the yard and the 4/4 is not flat enough over 3' to reach 7/8", the 9' stock has bad splits at the ends, all the nice boards are 7 1/2" wide and the 5/4 has better figure anyway! Now thats going to throw off your BF equation considerably.

    I encourage you to use your eyes and brain to hone your stock purchases as much as possible and rely on BF calculators for rough cost estimations and little else. Given all the variables in a complicated project, or even a simple one, the BF estimate is almost as good as a random number in my eyes. I like to understand my plans intimately then go searching for parts in the boards, not boards for the parts. Make sense?

  12. #12
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    Quote Originally Posted by Peter Quinn View Post
    You can punch a bunch of numbers into a spread sheet and churn out another number. That tells you how much lumber is in the finished product. What's tough is walking into a lumber yard and picking boards that agree with the spread sheet. Figuring the waste factor and minimizing it its the hard part and no computer is going to do that for you.

    You didn't mention species. Pattern grade mahogany? For me, add a 10% waste factor maximum. You couldn't build a bird house with the drops. Walnut? Add 40%, maybe more if things don't go well. Sap, sap, sap. Jatoba? There are lots of checks and cracks that seem to appear only in the bright light of my shop but never in the dim light of the lumber yard! White oak? If color matters you'll need to carry each board out into the day light, because they all seem to match under fluorescent light. Cherry? Good luck. Each species is a new adventure in beauty and frustration.

    My point is not to be a sarcastic mule here, but that it is a little trickier than developing some number plus a waste factor. Lots of variables. I rarely develop a BF number but always go to the lumber yard armed with a cut list, sometimes drawings too. I buy 4/4 for 3/4", sometimes if the stock seems flat enough and I'm feeling brave I'll call 4/4 7/8" finished. 5/4" up to 1 1/16", and so on. Rod's argument about adding 25% waste for the planer makes sense if you rely on a spread sheet and final dimensions, but I don't ever figure things that way. If a part calls for 3/4", I translate that to 1" rough in my head and calculations. By experience I know what I can expect to get out of an actual board best case scenario, and I remember to add 1/8" for each kerf plus as much as 1/4" for jointing.

    I mark up boards in the yard with a crayon or chalk, look for my parts in the stock, try to buy lengths and widths that fit my situation. I make a pile and check off parts as they are accounted for in my pile. Sometimes I change my design in the yard to suit what I find, other times that is not possible with in the scope of a project. Sometimes you need a 4/4 X 6" X 9' for a table top (say 18"X36") , but you get to the yard and the 4/4 is not flat enough over 3' to reach 7/8", the 9' stock has bad splits at the ends, all the nice boards are 7 1/2" wide and the 5/4 has better figure anyway! Now thats going to throw off your BF equation considerably.

    I encourage you to use your eyes and brain to hone your stock purchases as much as possible and rely on BF calculators for rough cost estimations and little else. Given all the variables in a complicated project, or even a simple one, the BF estimate is almost as good as a random number in my eyes. I like to understand my plans intimately then go searching for parts in the boards, not boards for the parts. Make sense?

    Yep, makes great sense! I really like the idea of marking the parts on the stock in the lumberyard. My initial thinking of BF calculation was just for price estimates, but I probably would have carried that to the lumberyard and used it for purchasing also. Seems like much less potential for waste looking for the parts in the boards. Thanks!

  13. #13
    I have to admit that I do not use the XL much for BF calcs. Maple and mahogany are as exotic as I go, so I just double what I think I might use. That way I will have some extra. If I keep a little buffer around I dont get upset Satuday afternoon when I am 5BF short from being done, and the only place to buy more is Borg.

  14. #14

    My apologies, Rod

    I didn't realize that cutting lists were based on finished dimensions. That could be confusing to a newbe.
    Live and learn.

    Tony B

  15. #15
    Join Date
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    1,795
    I rarely use board feet as a measure of how much stock I need to buy for a given project. It's much more convenient to know that I need this many boards so long by so wide by how thick to yield the collection of parts needed for the project. Cutlist Plus (CP) was mentioned as a solution, and is quite good for minimizing waste/maximizing yield for sheet goods. Not as efficient for dimensioned lumber.

    CP will certainly layout parts onto dimensioned stock and give the so many boards of such and such dimensions requirement. You just have to be sure that you tell CP what actual/finished dimensions the nominal/rough dimensions yield; 4/4 nominal = 3/4 actual, 6" nominal width = 5 1/2" actual width, etc. But the program does not, nor can it, take into account grain patterns or board defects that cause you to change the layout of auto-generated cutting diagram.

    So I'll usually let CP layout a cutting diagram to find the (minimum) number of boards needed in what sizes, then buy a couple of extra to take care of the in-process cutting diagram changes or parts laying across board defects. Works pretty good and usually keeps me from buying excessive stock and/or winding up with a stack of cutoffs that are all 1/2" too short for that last part.
    Tom Veatch
    Wichita, KS
    USA

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