# Lumber Yard Math



## NoSpace (Jan 2, 2015)

Curious how others deal with the most vexing part of buying wood: lumber yard staff counting up board feet. It's not rocket science, but it's on the more abstract end of consumer level math and the average person on the street just isn't used to thinking mathematically. I myself use an excel spreadsheet just to be sure (something these lumber yards, which tend to be pretty old school, haven't discovered yet, apparently).

I've only been buying hardwood at lumber yards for about 3 years now, and so I probably have less than ten trips under my belt, but most of those purchases-unless I'm buying a pre-marked slab of hobby wood-somehow involve me worrying about the calculation of board feet by the staff. In fact, I've in the past selected pieces of a certain dimension simply because it looks easy to count. There's not a huge amount of money on the line for me given I'm typically working on smaller projects, and so there's a humorous side to watching a person who sucks at math wave a baton around and write up a ridiculous bill, but at the same time, I don't like being charged double and I'm not the confrontational type so often I've just let it go if I don't think it's off by too much. I imagine serious woodworkers who rely on making that profit margin could wind up pretty frustrated.

I entered my fourth lumber yard a couple days ago after moving to check out the lumber scene in my area and picked up a hefty maple board and a small strip of walnut and a small strip of rosewood. When I got to check out, this guy walks up and pulls out a tape and a baton and goes to work, and he just looks utterly confused. Measurements aside, one would think it would give pause that the skinny strip of rosewood came up to 4 board feet, nearly what he'd counted, 6 bf, for the hefty maple board. It was obviously so far off that I stopped another worker, and then he, the original guy, and the foremen all head to the foreman shack and have a big conference for several minutes. They return with a verdict that cut my bill in nearly half. I didn't say anything, but why don't they have some online calculator pulled up or use a spreadsheet? they could save gobs of time and frustration.

In another incident, I have this young kid making a mess of 12/4 walnut slab count-kid had a great attitude and I wasn't mad or anything-and the owner stepped in on that one before I said anything. But at the same time, the owner's wife is waving the baton over my other boards and she wasn't doing much better. I questioned her, and you know, she'd been doing it for years and years obviously, but she comes up with some explanation for her method that makes no sense whatsoever to me. I'm doing my internal calculations and she was a really cool lady and I just didn't have it in my to push it given I didn't think it would be that much off. At home I measured exactly and overpaid by about 30$ maybe, which isn't the end of the world for 3-4 trips a year, but still. I told myself after that incident, I'd bring my laptop and show them exactly what the count is prior to them measuring (and I realize the have rounding rules etc. but that doesn't account for the discrepancies), but then life went off the rails a bit and I didn't buy wood again for about a year-the incident from a few days ago.

On the one hand, I want to pay what's fair, but I don't want to be a total jerk either by dragging out a spreadsheet and lecturing over a typically < $100 purchase. curious what others do.


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## Andybb (Sep 30, 2016)

I too have about the same level of experience as you in buying and pricing hardwood and am just as confused on the fly. Board feet, linear feet etc.

What I usually do is call ahead or get a general idea of what I'm about to spend before I leave the house using an app or web page then head out to the lumber yard.

I just trust that they are honest. The woodworking community is relatively small. There would be all sorts of negative Google comments and reviews if they were not being honest and truthful IMO. I think that if I had an experience like yours I'd shop somewhere else. Could be that the guy was genuinely inexperienced. The woodworkers in your area can tell you where to shop.


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## RichT (Oct 14, 2016)

I have the Construction Master app on my iPhone and calculate each board before I head up to pay. Not that multiplying length x width x thickness in inches and dividing by 144 is difficult, but most of the boards are 8, 10 or 12 feet long and the CM app deals with units nicely.

The guys at my local yard, Woodworker's Source, know their stuff, and are quite generous when it comes to measuring. The ticket total usually comes in below my estimate, but it's still a good idea to have a ballpark idea in case there is a mix up.

If I had to deal with clueless people frequently, I'd probably consider carrying a pad of Post Its and a pencil and mark each board's dimensions and BF before I went to pay.


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## Ripper70 (Nov 30, 2015)

There are a few board foot calculators available for the iPhone and, I'm guessing, Android as well. Pretty straightforward and simple to use.


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## RichT (Oct 14, 2016)

Also, if high-tech isn't your thing:

https://www.popularwoodworking.com/woodworking-blogs/the-lumber-rule


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## JayT (May 6, 2012)

Board feet measurement can be a problem. Some of the guys that are really good employees because they are good at other aspects of customer service and lumberyard duties just can't wrap their minds around the necessary math. If a lumberyard knows that, why not come up with a way to avoid the hassle?

The hardware stores where I work sell some hardwood. Our solution is that when lumber comes in, one person who knows what they are doing marks each board with the board foot amount, price per and total cost for the board as it is being sorted and stacked. Because it's being done all at once when the lumber is being handled anyways, it actually takes less time than to do it when a customer is purchasing and may be waited on by someone who isn't good at calculations. It's also just good customer service. The customer is able to get in and out faster and leaves no question what they are buying because they can see it before deciding to purchase.


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## Redoak49 (Dec 15, 2012)

I tend to go to a place I trust for being fair. Not only are measurements important but also the number, kind and severity of defects. Just give me a fair deal..


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## WDHLT15 (Aug 15, 2011)

I sell a lot of hardwood lumber. Many of my customers are confused by board feet. I have to explain it a lot. It is simply a square foot of surface area one inch thick as you guys know. However, looking at a 9" board 11 feet long for example, the amount of surface square feet is not obvious, and for some, hard to envision.


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## NoSpace (Jan 2, 2015)

Andybb-"I just trust that they are honest. The woodworking community is relatively small. There would be all sorts of negative Google comments and reviews if they were not being honest and truthful IMO"

It's not so much about honesty but a skill that may be hard for the average otherwise hardworking employee to incorporate (JayT's comment), combined with an old-school manner of doing business (that weird measuring stick that aids in calculation I call a baton) where old habits die hard. as WDH points out, customers are just as confused so it may be something like the blind following the blind. Perhaps the guy with the experience shows up for bigger buyers and less of an issue, but I've seen the problem in enough places now that I'm guessing it exists just about everywhere so yeah, I'm really curious why there aren't complaints or what others experiences have been.

WDHLT15-"I sell a lot of hardwood lumber. Many of my customers are confused by board feet. I have to explain it a lot."

Sure-but what about your employees? 

The last guy who rang me up at this new store I went to the other day (who would have charged me double) figured it out with a pencil and notepad. I'm pretty good at math and I wouldn't even try that. How does your staff tally up the final count for the customer?


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## jonah (May 15, 2009)

I have to say that across the half dozen hardwood suppliers I've been to, I've never had this experience. Most people rightly multiply length, width, and if necessary, thickness, then divide by 144.

I have a good idea about how many board feet the boards I select are, since that's a relatively easy in-your-head calculation.

If anyone ever tried to overcharge me I'd most certainly say something. I'd start politely, but if I felt like it was not an honest mistake, I'd walk out.


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## MadMark (Jun 3, 2014)

Remember that you're buying the full rough cut blank, not the trim size. You need to calculate with the full nominal size, not the reduced size. A 2×4 is 1-1/2 by 3-1/2 but you pay for the full 2×4. Now 4" is 1/3 bf / ft, times 2 for the thickness means every lineal foot is 2/3 bf. But if you use the final 1-1/2×3-1/2 dimensions every lf is .4375 bf instead of 2/3 bf (.666 bf) so right there the actual cost is 1/3 more than your estimate using a ruler.

Hope this helps.

M


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## RichT (Oct 14, 2016)

> Remember that you re buying the full rough cut blank, not the trim size. You need to calculate with the full nominal size, not the reduced size. A 2×4 is 1-1/2 by 3-1/2 but you pay for the full 2×4. Now 4" is 1/3 bf / ft, times 2 for the thickness means every lineal foot is 2/3 bf. But if you use the final 1-1/2×3-1/2 dimensions every lf is .4375 bf instead of 2/3 bf (.666 bf) so right there the actual cost is 1/3 more than your estimate using a ruler.
> 
> Hope this helps.
> 
> ...


That's nonsense. Since when are 2 by 4s sold by the board foot?

Like Jonah and I said, length times width times thickness (all in inches) divided by 144. That's it. The closest thing to your explanation is that S2S is based on rough size. A 4/4 board is considered 1" thick for BF calculations even if it's been surfaced down to 7/8" or 13/16".


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## alittleoff (Nov 27, 2014)

I've bought lumber a few times and about everyone measures the board correct except for thickness. Most all will figure the board at 1 in. Even if its a half inch thick. I don't mind it if its 3/4 ", but I think they should cut it at half in. What do you think? 
Gerald


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## bondogaposis (Dec 18, 2011)

Boy, it is really simple math, I don't see how anyone that works in the lumber business, shouldn't be able to master it with a simple hand held calculator and a tape measure. It is L x W x T in inches /144 =bf. On 4/4 stock you can ignore the thickness. I guess I'm lucky in that the guys I buy from know their stuff.


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## Carloz (Oct 12, 2016)

I am too shy when it comes to arguing with people, who have much better experience than I including counting the lumber. But I wonder how it is possible do do quick a measurement of 100 bf of lumber from one side only, then counting the boards and putting some number on the invoice. Almost all boards have different width on the opposite ends and some of them are usually few feet shorter than the rest. So if it were me I at least would measure the width in the middle and also measured all odd length. But apparently they know better.


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## cathode (May 18, 2014)

Where I am, the two hardwood distributors I've visited both mark each board with a 3 letter code or abbreviation of the wood species, and the number of board feet. They round to the nearest half-board-foot. Sometimes, boards with significant issues, like a split in the end longer than a foot, or a really large knot, will be circled or marked with chalk and they subtract that from the marked board footage, which is nice.


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## jonah (May 15, 2009)

^^

I've never understood why more hardwood places don't do that! It seems like a no-brainer to me.


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## bigblockyeti (Sep 9, 2013)

> Boy, it is really simple math, I don t see how anyone that works in the lumber business, shouldn t be able to master it with a simple hand held calculator and a tape measure. It is L x W x T in inches /144 =bf. On 4/4 stock you can ignore the thickness. I guess I m lucky in that the guys I buy from know their stuff.
> 
> - bondogaposis


If I were hiring someone to work with lumber where being able to calculate bdft., they would first pass a short written math test with no calculator, spreadsheet or phone, long hand only. Extremely basic skills for too many people are being completely overlooked as being important by most of society. In thirty years we'll have PhD's that can't wipe their own rear because it's not their area of expertise.


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## bigblockyeti (Sep 9, 2013)

> Boy, it is really simple math, I don t see how anyone that works in the lumber business, shouldn t be able to master it with a simple hand held calculator and a tape measure. It is L x W x T in inches /144 =bf. On 4/4 stock you can ignore the thickness. I guess I m lucky in that the guys I buy from know their stuff.
> 
> - bondogaposis
> 
> ...


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## Carloz (Oct 12, 2016)

> ^^
> 
> I ve never understood why more hardwood places don t do that! It seems like a no-brainer to me.
> 
> - jonah


Because many places let you cut a part of the board, especially thicker and more expensive ones. So once you do it the previous measurements make no sense.


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## MadMark (Jun 3, 2014)

2×4 was an example, try the math on a 1×6 that is 3/4×5-1/2" x6'

The rough mills only cut down to 4/4 normally. Again to make a 1/2" thk piece they have to start with a full 4/4 board.

This is also why the board widths go up by 2" increments, much easier to figure when doing in the head math.

Remember too that all of this board ft math goes wayyyy back before spreadsheets & calculators. It actually is easy to think it out. Convert the width to a fraction of bf by dividing 12 by the nominal width (not the final width). A 3/4×5-1/2 piece is cut from a 1×6 and is thus is 1/2 bf per lineal foot so a 12' is six bf - easy peasy.

M


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## RichT (Oct 14, 2016)

> 2×4 was an example, try the math on a 1×6 that is 3/4×5-1/2" x6


You're still talking about dimensional lumber. That's the crap they sell at home stores, and they sell it by the linear foot. Yes, you can work out a bd ft number from it, but that's not how it's sold. Same for 2x lumber, you buy an 8 foot, or 12 foot board for one unit price. There's no board feet involved, unless you feel like playing with your calculator for the fun of it.

This thread is discussing rough or S2S lumber. For FAS through Select, the boards are 4" wide and up and 8 feet long and longer. You pay for what you get, so if a 4/4 FAS board is 7.5 inches wide by 10 feet long, that's 6-1/4 bd ft, period. You pay for the exact dimensions of the board (minus the surfacing like I said earlier). That said, as others have mentioned, a good lumber dealer will account for boards that aren't the same width down their full length or have checks - things that affect the yield.



> This is also why the board widths go up by 2" increments, much easier to figure when doing in the head math.
> 
> M
> 
> - Madmark2


Again, head down to a real hardwood dealer. You'll find boards that are 6-1/2", 5-3/4" and other widths.


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## jonah (May 15, 2009)

> ^^
> 
> I ve never understood why more hardwood places don t do that! It seems like a no-brainer to me.
> 
> ...


I'd write it with a chalk pen for exactly that reason. You just erase it and write the new figure. Or just scratch it out and write a new number next to it.


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## NoSpace (Jan 2, 2015)

Pre-measuring is a good idea, but as Carloz said, some places still cut tops to your specification as long as you leave 8'.

As for "math before spreadsheets and calculators" - and don't forget measuring before the spring-loaded tape measure - this is part of the problem. Both cases I cited from two different yards involved the use of an old-school tool called a scaling rule:

https://www.benmeadows.com/conway-cleveland-lumber-three-line-scaling-rules_36810591/?gclid=EAIaIQobChMIkvzc8YGI1wIVFFqGCh34bAJvEAQYASABEgIhjPD_BwE&selectedsku=121721&CID=BMPL10&s_kwcid=AL!3210!3!55826733178!!!g!130343117578!&ef_id=Wc8RfwAAAyVBrGkY:20171024003555:s

Why does such a thing still exist?

It's just an old-school industry; for the same reason government facilities might run DecNet I guess. Anyway, that thing makes calculation "easy" by a dimension chart where the length is estimated (by the employee first hopping the rule over the board to get the length), I assume the width is considered 1, and the width is then measured and a chart shows the BF calculation. Well, I don't think such a thing is easy compared to a calculator or an app and lots of room for error, but if that's the way the owner learned it 30 years ago then that's the way it's done I guess.


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## RichT (Oct 14, 2016)

> I d write it with a chalk pen for exactly that reason. You just erase it and write the new figure. Or just scratch it out and write a new number next to it.
> 
> - jonah


A little off-topic from lumber yards per se, but I use lumber crayons to mark species and dimensions on boards when I bring them home. That way I can glance through my stack and see what works for what I need at a given time. I also mark what lot they are from, since I might buy the same species on multiple visits depending on what's on sale. 
I tried keeping a spreadsheet of inventory, but that was too much of a hassle to maintain.


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## Lazyman (Aug 8, 2014)

BF calc is very simple. Use the calculator on your phone and simply measure the exact length, width and thickness, all in inches. Multiply the 3 measurements and divide by 144.

Now if it has major defects, you can try to get some taken off for unusable wood. Either that or have them cut the defect off and don't pay for it.


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## AlaskaGuy (Jan 29, 2012)

We have to remember, hardwood and softwoods/construction lumber is sold differently.

http://www.wagnerlumber.com/Lumber/What-are-Board-Feet/


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## WDHLT15 (Aug 15, 2011)

*"WDHLT15-"I sell a lot of hardwood lumber. Many of my customers are confused by board feet. I have to explain it a lot."

Sure-but what about your employees? "*

I do not have any employees. If I did, they would be properly trained.


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## el_mustango (Oct 26, 2017)

I'm glad I'm not the only person who feels like even employees at the lumber yard have trouble with this. I like the idea of just using an app before I take my boards to the register just so I have an idea of how much they should be charging me. Any one use an app (ios preferably) that they recommend?


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## Geraldsh (Oct 29, 2017)

This thread came to mind today when I was looking a piece of cherry 1"x12"x12'. A young helper came by so just for fun I asked "How many board feet is this?" He tells me he is sorry and he will send over someone who knows. At least "Someone Who Knows" was able to whip out a tape to check the length and width and quote a price within a minute.


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## Lazyman (Aug 8, 2014)

> I m glad I m not the only person who feels like even employees at the lumber yard have trouble with this. I like the idea of just using an app before I take my boards to the register just so I have an idea of how much they should be charging me. Any one use an app (ios preferably) that they recommend?
> 
> - el_mustango


Yes, the calculator app, (Length x Width x Thickness) / 144
Make all your measurements in inches. Probably too simple for someone to bother making a dedicated app.

I always check the measurements they put on the boards in advance. Sometimes they've cut them after initial measurements were made and sometimes they round up their measurements to nearest quarter or half inch which can make a huge difference on a long expensive board.


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## NoSpace (Jan 2, 2015)

"Any one use an app (ios preferably) that they recommend?"

someone earlier in the thread mentioned the "construction masters" app. another linked to a web page you could hold open if you go back to page 1.

I have an iTunes account problem i haven't dealt with in too long, but when I get around to it, I'll find a spreadsheet. I use open office on my computer.

To me the spreadsheet is the way to go because then you can have as many fields as you want and if you get price quotes you could even have a running total for the whole bill as you look around. On mine I also had a field for their calculation and how much they were off by. that was on my laptop that now I realize i no longer have because I changed jobs. Anyway, having that saved I could look at the kind of dimensions that gave them issues. In my cases the lumber "scaling rule" they used I believe introduced confusion, i mean, it's a really lame legacy way to do things.


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## RichT (Oct 14, 2016)

> "Any one use an app (ios preferably) that they recommend?"
> 
> someone earlier in the thread mentioned the "construction masters" app. another linked to a web page you could hold open if you go back to page 1.
> 
> - NoSpace


That was me. It's Construction Master Pro by Calculated Industries. Back when I bought it, it was $9.99 which was a great deal since the physical calculator sells for about $50. I just looked it up to make sure I had the info right, and I see it's now $24.99, which really sucks.

It does far more than BD FT. You can read about it and see if it is worth the price for you, but I use it all the time for fractional calculations, rise/run, arcs and radiuses.

However, at $25, it might be hard to justify.

Another app that's I use in place of spreadsheets is called Soulver. It's $3. I have documents set up that do all sorts of estimating for bids. One I use all the time is for residential doors. I can look up the BD FT price for 4/4 and 8/4 lumber online at my local hardwood dealer and enter those figures along with the dimensions of the door and it will give me the cost for lumber to build the door and also the cost + my waste estimate that I use for the actual bid.

Another one does lower cabinets. I enter dimensions, number of doors/drawers and it tells me lumber cost + hardware.

Finally, if you're good with programming Python, the Pythonista app allows you to build stand-alone apps for IOS without going through the Apple Developer Program and messing with Swift. It's pretty impressive to be able to sit with a client and work out options on what appears to be custom, branded apps on your iPhone or iPad.


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## el_mustango (Oct 26, 2017)

> Yes, the calculator app, (Length x Width x Thickness) / 144
> Make all your measurements in inches. Probably too simple for someone to bother making a dedicated app.
> 
> I always check the measurements they put on the boards in advance. Sometimes they ve cut them after initial measurements were made and sometimes they round up their measurements to nearest quarter or half inch which can make a huge difference on a long expensive board.
> ...


Haha, yes I suppose just using the calculator would work. But, that would require me to remember an easy formula and to do some simple math. What is this- the early 2000s?? But seriously, I guess an app would be unnecessary. So thanks for reminding me that sometimes we don't have to rely on our phones for everything.



> To me the spreadsheet is the way to go because then you can have as many fields as you want and if you get price quotes you could even have a running total for the whole bill as you look around. On mine I also had a field for their calculation and how much they were off by. that was on my laptop that now I realize i no longer have because I changed jobs. Anyway, having that saved I could look at the kind of dimensions that gave them issues. In my cases the lumber "scaling rule" they used I believe introduced confusion, i mean, it s a really lame legacy way to do things.
> 
> - NoSpace


Using a spreadsheet is a great idea, especially to keep a running total if you were buying a lot of wood.



> That was me. Its "Construction Master Pro": https://itunes.apple.com/us/app/construction-master-pro/id370406446?mt=8 by Calculated Industries. Back when I bought it, it was $9.99 which was a great deal since the physical calculator sells for about $50. I just looked it up to make sure I had the info right, and I see it s now $24.99, which really sucks.
> 
> It does far more than BD FT. You can read about it and see if it is worth the price for you, but I use it all the time for fractional calculations, rise/run, arcs and radiuses.
> 
> ...


I saw Construction Master Pro when I searched on the App Store, but it was overkill and too expensive for my needs. But thanks for sharing, as I am sure it could work really well for others.


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## AZWoody (Jan 18, 2015)

> Yes, the calculator app, (Length x Width x Thickness) / 144
> Make all your measurements in inches. Probably too simple for someone to bother making a dedicated app.
> 
> - Lazyman


Do an app search for "board foot calculator" and there are several apps that calculate board foot. Some are simple while others calculate costs and other things along with it.


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## MrRon (Jul 9, 2009)

I believe "bd ft" only applies to rough milled wood as in 4/4, 5/4, 8/4, etc. Once it has been milled down to "nominal" dimensions, it gets priced by the piece. A board i" thick x 12" wide x 3' long would be 3 bd ft, but a board 3/4" thick x 12" wide x 3' long would be 2-1/4 bd ft, but would reflect the cost of the 3 bd ft. You end up paying for the waste from milling from a standard bd ft.


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## AZWoody (Jan 18, 2015)

> I believe "bd ft" only applies to rough milled wood as in 4/4, 5/4, 8/4, etc. Once it has been milled down to "nominal" dimensions, it gets priced by the piece. A board i" thick x 12" wide x 3 long would be 3 bd ft, but a board 3/4" thick x 12" wide x 3 long would be 2-1/4 bd ft, but would reflect the cost of the 3 bd ft. You end up paying for the waste from milling from a standard bd ft.
> 
> - MrRon


I have never seen that in a hardwood dealer. If it's S2S and 3/4", then the price is for 3/4" and priced as S2S, which means surfaced, 2 sides. So there is an extra cost to it for the work done.

That's why lumber is designated by the 1/4 in terms of thickness. 1 1/2" thick piece is labeled as 6/4 lumber whether it's rough or surfaced. You pay for what you buy in thickness but you also pay for the amount of work done to get it to a ready to use product.


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## AlaskaGuy (Jan 29, 2012)

> I believe "bd ft" only applies to rough milled wood as in 4/4, 5/4, 8/4, etc. Once it has been milled down to "nominal" dimensions, it gets priced by the piece. A board i" thick x 12" wide x 3 long would be 3 bd ft, but a board 3/4" thick x 12" wide x 3 long would be 2-1/4 bd ft, but would reflect the cost of the 3 bd ft. You end up paying for the waste from milling from a standard bd ft.
> 
> - MrRon


My supplier only sells hardwoods. Everything is sold by the board ft. In the rough, s3s or s4s. Pick out the wood you want and lay in on some saw horses, then the employee measures it.

Big slabs like of a table top they will mark the full price on.


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## TungOil (Jan 16, 2017)

I made this up many years ago to make it easy to calculate board feet at the yard.










I have it marked for 8, 10 and 12 foot long boards- 4/4 on one side, 5/4 on the other.

for 16' lengths, double the 8' reading. For 8/4, double the 4/4 reading, and so on. I've not come across a board i could not measure with it in the 20+ years since I made it.


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## kelvancra (May 4, 2010)

I agree with the "a 3/4 inch board is a 1" board" thing, except with regard to 2x's used for framing and such. Those are sold by the 2x according to their width.

As to the matter of figuring bf, get a calculator. They are only three bucks. After that, all you have to remember is what others said:

1) Multiply thickness by width times length, all in inches
2) Divide by 144 (12×12 for a 1" thick board foot)
3) Add the [same kind of] boards together

Done

Anything that doesn't fit the rules was, probably, an honest mistake and should be pointed out as such. Hand them your calculator, if need be.

PS One supplier sells both nominal (rough, 1") stock and S2S. The S2S is 3/4 and is treated like the nominal stuff.


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