how many mbf in a cord of wood?? (oak)

[a old timberjack]

 i been looking all over, i read it somewhere how many board feet in a cord of wood 128 cubis feet 4x4x8 i guess it is a stupid everyday question you always forget., thanks....... Brandon

[Gary_C]

The conversion depends on both the diameter of the logs and the bd ft scale you use. But despite that most people use the standard factor of 500 bd ft per cord or 2 cords per MBF.

[ljmathias]

Still trying to get my mind around this- so 4X4X8 is the same as 2X4X16.  So if I had 16' logs, 12" in diameter, I could lay down two logs wide (2') and stack them four logs high, right?  That means 8 12" logs 16' long- how would this scale out then, same as indicated at 500 bdf?

Lj

[Phorester]

Nope.

If you were dealing with nothing but cubic feet of solid wood, say two boxes of wood chips or sawdust, then both 4x4x8 and 2x4x16 will give the same volume.

But that won't hold up when dealing with real logs.  Remember that logs aren't perfect cylinders, there is taper from one end to the other.  Most volume tables are based on the diameter inside the bark (dib) of the small end of a log.  So the question needing an answer is, where on the log would your 12" diameter be measured? 

That means the analogy of 4x4x8 versus 2x4x16 won't hold for bd ft or cord comparisons, even though it's the same cubic foot volume.

[Tom]

It's also important to realize that you are using two different measuring scales.  Board footage, is used for determining the lumber or timber, by volume, in sawlogs.  The board footage scale uses inside the bark measurements and is written to favor certain sizes of logs. 

Generally  a cord is considered 4'x4'x8' of split and tightly stacked firewood.  Sometimes a cord is a weight measurement in the neighborhood of 5500 pounds, depending on species, size nad weather.

Accept for some local communication, Face cords aren't a legitimate measure and are not used legally to report sales.

The quantity 500 board feet per cord is just a general rule of thumb that approximates the board footage in a scaled or weighed cord.  Variables that would effect it are log size, branches, knots, holes, rot, sweep, as well as the type of  mill used to break it down.

[Climber]

Theoretically / mathematically ONLY
1 cord = 4x4x8 = 128 cubic feel
board foot is 1"x12"x12" or 1/12 of cubic foot
12 BF is 1 cubic foot
12 BF in each cubic foot x 128 cubic feet in cord = 1,536 BF in cord.

It is theoretically / mathematically ONLY and NOT practically
Climber

[Rocky_Ranger]

It's also an apple and an orange, your board foot is solid and the 4X4X8 is not.  Solid cords run 75 - 85 cubic feet of wood.  Depends on the log size, and the fact most "cubes" figure on Smalian's formulas.  Nat Cruise figures cubes and boards, they run the gamut from 425 bd ft/ cord to 675 bd ft/cord.  Maybe even more, those arre just the ones I see - mainly around 550 bdft/cord.

[Jeff]

Theoretically / mathematically ONLY
1 cord = 4x4x8 = 128 cubic feel
board foot is 1"x12"x12" or 1/12 of cubic foot
12 BF is 1 cubic foot
12 BF in each cubic foot x 128 cubic feet in cord = 1,536 BF in cord.

It is theoretically / mathematically ONLY and NOT practically
Climber

Absolutely not practical, or possible.

[ljmathias]

Hey, thanks for all the great replies: I think I'm getting it but stop me if I'm wrong- trees are round, boards are flat... or am I getting close yet?

Lj

[Blue Sky]

A cord of wood in these parts is a stack of wood 4x4x8.  Green 4' logs.  When you cut that stack of logs up into cut and split pieces, it reduces to a stack approx. 100 cu.ft.  Is this true, anyone out there.    Enchanted Forester

[RSteiner]

I have always wondered why or how the unit of measure for cordwood would be used for measuring lumber.     Both are volume measurements but in a very different form. 

Lumber measurement is the volume of one solid piece where cordwood measurement is the voulme of space many pieces take up.  An old Machinery's Handbook I have lists the volume of a cord of wood as 128 cubic feet, a pile 4'X4'X8'.  They figure a pile of cordwood to contain a solid volume of about 70 cubic feet, so 58 cubic feet of the cordwood pile is air.
I think the soild wood number for cordwood is more for determining weight than BF volume.

At those figures there would be 800 BF to a cord of wood.  That could be high depending on the diameter and defects in a log.  The 500 BF figure sounds more like it.

Randy

[maineframer]

Around here white cedar is sold by the cord, not by the thousand. That rule of thumb is helpful.

[woodmills1]

the max I can get on my trailer is 1500 bd ft of logs and it holds 3 cord of firewood......do the math.

[SwampDonkey]

The loggers and wood cutters here are old school. They only understand cords, something they can scale off with a 4 foot pulp stick. Tonnes, board feet, m³ and they want it converted.

[Gary_C]

Let's change the question slightly. If you are looking at a standing tree, how do you determine the cords or MBF in that tree?

Say you are marking a stand for cutting. You look at an 18 inch DBH Hard Maple and you know all the trees in this stand are 60 feet tall. In one case say the tree will not make a sawlog and it is pulp. How many cords?  In the other case, it is a log tree. How many MBF?

[SwampDonkey]

We mark based on basal area, crown closure, and quality. And stands are rarely marked here, wouldn't be 1% of harvested volume. We tried to push it for years, but it didn't take. Only thing that's marked is perimeter and trails on 99.99% of sites. In mature hardwood and softwood 24 m²/ha equals 24 cords/acre as a rule and used as a quick figure before doing the math at the office. And believe it or not it's very reliable.   Mature cedar, hemlock and white pine throw that out the window because of taper. White pine for instance grows 15 meters taller than spruce and fir.  We measure and compile based on metric m³, and convert to cords using figures for 8' wood, or 4 if there is a 4 foot pulp market. Log volume is a crappola shoot for hardwoods and no one up here scales hardwood logs on standing trees. As a general rule for 'potential' hardwood sawlog trees we equate 60-70% of the volume to pulp and 30 % of the softwood sawlog volume is pulp. Anything smaller than spec is just pulp. Because quality is so poor in hardwood, it is bid on for pulp and sometimes a deal is struck to pay 50% of log price for good logs and veneer.

[Gary_C]

I guess I have some idea how you scale a tree for MBF from DBH, but are there tables that give you cords based on DBH also?

[Ron Scott]

Yes, there are board foot tables and cordwood tables to determine a trees volume in board feet or cords. There are also cubic foot tables.

When marking and cruising the timber we determine if the tree is sawlog or pulpwood by species, size, and quality and then record the tree's diameter and merchantable height. This data is then entered into a computer program which determines the trees volume by board feet to an 8 inch top (International 1/4 scale) and cordwood to a 4 inch top, plus any additional cordwood in the topwood.

The computer then calculates the total MBF and cordwood volumes by species for sale. 

[RSteiner]

This is all very interesting.

Randy

[Phorester]

From Gary_C:    "......but are there tables that give you cords based on DBH also?"

Yep.  Want me to mail you one?