This is a measure of a wood’s weight in relation to a preset volume. Usually it’s pounds per cubic foot (lbs/ft3), or in metric units: kilograms per cubic meter (kg/m3). However, a wood’s weight will also greatly depend on it’s moisture content (MC). For instance, a board that has just been freshly cut (called “green” wood) can weight more than double its oven-dry weight! Since there are so many sources of information on wood properties, and not all of them use the same standards and testing procedures, there can be a great variety in weight readings.
I’ve made every effort to standardize all readings to reflect the weight at a 12% moisture content; this is the most common standard of measurement for nearly all wood testing conducted worldwide. A moisture content of 12% is attained when a wood sample has reached equilibrium moisture content (EMC) with the surrounding air at a temperature of 70°F and a relative humidity of approximately 65%. Storing wood in areas where the relative humidity is lower than this will result in a lower moisture content, and therefore a correspondingly lower density.
Take time to compare a density reading to another well-known wood, and see how it measures up. For instance Red Oak is about 45 pounds per cubic foot, (or 730 kilograms per cubic meter), which in and of itself isn’t too terribly useful, seeing as how you will most likely never encounter (or be required to lift) a piece of oak that is a perfect one-foot (or one-meter) cube. However, if you make a mental note of this weight, and use it to gauge other woods, you can quickly get an idea of how much things weigh. (For example, you can quickly see that Western Red Cedar weighs about half as much as Red Oak, but Lignum Vitae’s weight is almost double that of Red Oak!)
Additionally, in general terms, a wood’s density can be used to deduce a number of things about a wood’s properties; i.e., hardness, strength, etc. The heavier a wood is, the harder and stronger it is, in general.
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Eric, I applaud your effort to provide numbers that are useful to woodworkers, and not the strange numbers provided by the US FPL (“weight when ovendry and volume when green or at 12% moisture content”).
But how do you get these numbers? Is there another source besides the FPL? Or do you do some sort of adjustment to it, perhaps using the volume shrink rate?
The FPL almost always publishes both numbers, so in most instances a value at 12% MC is available (along with a number of other sources). See here: https://www.wood-database.com/references/
But in very rare instances, yes, it’s possible to approximate these numbers if you have both the basic specific gravity and also volumetric shrinkage.
For example, FPL gives the SG at 12% MC of American Beech as 0.64. You give it as 0.72, and average dried weight as 720 kg/m3.
What is your formula for getting this 720 value?
When it comes to the SG at 12%, I don’t use a formula to derive the average dried weight, rather its vice versa. The SG at 12% MC is just the average dried weight (metric units kg/m3) divided by 1000. For the life of me I don’t know why the USDA Wood handbook doesn’t just list the average dried weight directly. To my knowledge, the number they list for 12% SG is not a literal measurement of any wood sample but a double standard similar to the “basic SG” oven dry weight and green volume (non-existent). I rant about how… Read more »
OK, third time’s the charm, I’ll ask it very generically: how do you get the 720 value?
What is your source (for American Beech at 720), or
what is your formula, or
did you measure it yourself?
By the way, the “edit” feature doesn’t work. It always says “you’re making edits too fast” (or something like that), and refuses the edit.
The value comes from “Hardwoods of North America” by Henry Alden. But that book is also put out by FPL and uses the same data as the Wood Handbook, but also includes dried weight.
I use to haul alot of Canfor dimensional spf lumber to building material centers,occasionally I would be required to weigh the load(from railcar) to match wt.to boardfeet(normal load was 49,000#) & was correct,or “very”near bill of lading calculated wt. Question: how many boardfeet would be on the truck ?
Since we are talking about average weight here. Does anyone know some normal deviation of weights of some same species?
I know some instrument builders tend to grade the woods they use. Do the different grades of same species have noticeable weight differences?
Thanks!!
I believe the USDA lists a standard deviation in density for tested woods at +/- 10%.
As for different grades effecting weight, I suppose that would depend on the species. With softwood species such as spruce, the higher grade old growth pieces I’m sure have a higher weight, but that may not be true with other kinds of woods, such as some hardwoods.
For dried construction lumber i.e. SPF, you will rarely (if ever) find wood dried down to 12% since the grading standard for kild-dried (KD) lumber is 19% or better.
I have to estimate the weight of an antique Rosewood desk for shipping purposes. My calculation of cubic centimetres is 82 000, what would you recommend as a weight per cubic cm? Many thanks, neil fraser (pastor)
A good baseline for rosewood would probably be 800 kg / cubic meter, or about .8 grams per cubic cm.
Take a set of scales and 3 pieces of wood; place the scales under one corner and a piece of wood under the other three corners to keep the desk level. If the desk is symmetrical then x 3 = total weight. If the desk isn’t too heavy you may be able to weigh one side and multiply x 2. Most freight companies have an online calculator – enter dimensions so they can calculate cube weight, which is considered against actual weight.
How much does a cubic foot of mesquite wood weight?
what is the average weight of a mature eucalyptus tree in kenya.
The answer to the weight of a mature eucalyptus trees in Kenya
trying to figure out the weight of 1000 sq ft of 150 yr old reclaimed spruce to build a tiny home thanks
1000 square feet at what thickness?
1 inch thick.also weight of 6×6 150 spruce beam 12 ft long thanks
Not sure what kind of spruce, but using a roughly average 26 lbs/ft3, 1000 square feet at 1 inch would weigh just under 2200 pounds. Also, a 6×6″ x 12′ beam would be approximately 78 lbs.
Thanks for your help
May i know the green weight formula for timber ?
or there is no formula like this ?
There is no formula for the weight of wood. A weight table for the specific species must be consulted.
Just to be clear, when you say wood moisture content, that is by weight right? Not moisture content by volume?
I may be wrong, but it sounds like Paulownia wood, a lightweight wood and really strong. Colloquially, it is called the aluminum wood. If you may have the weight of your sample piece, maybe you could get closer to the type of wood. Dry Paulownia weights about 265 Kg/m3. Very resistant to humidity, and even to fire. It will not twist or bend. Long durability. Very expensive wood. Yes, it is being grown in the USA.
Good luck
May I know the average dried weight (kg/m3)of timber as below,
1)average dried weight of Ulin timber
2)average dried weight of Jati timber
Do you have the scientific names of these timbers?
Ulin: Eusideroxylon zwageri. AKA Bornean ironwood, billan.
Jati: Tectona Gratis. AKA teak.
Many thanks for your work. Immense help in calculating the weight of an Oak table top I’ve been asked to build… over 400 lbs!! I think I’ll try to talk them into veneer….
Cheers!
https://www.charlesfreeborn.com
Sounds pretty massive. Just keep in mind that depending on how you build it, it could end up weighing about the same. Substrates such as MDF weigh approximately the same as oak when compared 1:1 by volume.
HI I am trying to get an idea of how many board feet would be in a ton of green spruce log.
Eg. if you get a load of green spuce logs approx 32ton how many board feet would you approx
get out of this load after sawing.
Thanks
Rob
Green spruce is around 33-39 lbs per cubic foot, depending on species. Assuming American tons (2000 lbs) that’s 64000 pounds. Averaging about 36 lbs, gives a vague result of about 1777 cubic feet, which translates to 21333 bf.
This, of course, does not factor in particular species, bark, or edge waste.
What a silly thing to say, “…which in and of itself isn’t too terribly useful, seeing as how you will most likely never encounter (or be required to lift) a piece of oak that is a perfect one-foot (or one-meter) cube. ” I have 100 one cubic metre rounds of oak and hornbeam that are more accurate in terms of size than of weight (given that weight is dependant upon moisture content). My length is accurate to within a centimetre or threeand given that each log is a maximum 10 centimetres and the bails or rounds were mechanically shaped, there… Read more »
Do you assume yourself a typical reader of this article, with your mechanically-shaped one-metre rounds? lol
Absolutely
your claim of having rounds that are cubes confuses me.
How much would dry pineweigh that is one inch thick twelve inches wide sixteen feet long.
16 BF, Pretty simple…
She asked for weight not board feet. Convert inch measurements to feet. Then multiply length x width x height x averaged dry weight. So in your example: 1/12 ft x 1 ft x 16 ft x 25 ft^3/lbs = 33.3 lbs.
x 25 lbs/ft^3 NOT x 25 ft^3/lbs. With ft in the denominator the ft cancel leaving lbs in the answer.
I would love to know how much a 6×6 of water soaked white line wood weigh as I deal with lifting that every day at work
Perhaps a little late, but should it help anyone…
If the wood is really soaked through to the core, the weight of water would be closer than the weight of dry wood. A cubic foot of water weighs about 62.4 pounds and most wood weighs less than that. I don’t see “white line wood” as a name in my Google results, so I’m not sure what species you’re referring to. 6×6 is not a volume, but is a profile of a quarter-square-foot, so most woods would likely be less than 15.6 lbs per running foot.
I am trying to find out what a 6×6 timber of black locust 26 feet long will weigh
Assuming the wood is a full 6″ and not 5.5″, that comes out to 6.5 cubic feet of wood volume. So Black Locust is about 48 pounds per cubic foot, so it would weigh 312 pounds.
But also note, if the moisture content is higher than 12%, it could easily weigh more than this.
thank- you for your answer this will be huge factor in my project
i am trying to figure out what a cubic foot of dry oak weighs?
About 45 pounds per cubic foot.
Hello, My friend ownes a named the Blue Goose Inn on Jefferson in Saint Clair Shores, MI 48081. This building was built on an island named Harsens on the Saint Clair River and in the late 1800s or early 1900s it was moved across Lake Saint Clair to its present location. Now, he is remodeling a portion of the builing and he had cut through a 2 x 4 and it was like going through butter. Now he gave me a piece, which is at true 2″x4″x 18″ and this piece is very light in weight and as strong as… Read more »