How Much Does Lumber Weigh?
Lumber weight significantly impacts lumber shipping options, material handling methods, structural design decisions and purchasing decisions. However, wood rarely ships with accurate weight information. Thus, woodworkers and lumber professions often must estimate weight.
A timber board has two mass elements – water weight and raw wood fiber density. Both factors comprise the lumber’s overall weight.
Surprisingly, the weight of a lumber board may vary over time. Typically, this is due to moisture gains or losses as a result of environmental changes.
Regardless, accurately estimating wood weights save woodworkers both money and problems.
The easiest and most accurate way to weigh wood is using a scale. unfortunately, unless you have a scale with industrial size weight capacity, most scales are useless for measuring large lumber boards. Accordingly, most woodworkers rely on estimation to quickly gauge the weight of a large board of wood.
Lumber Weight Is Based on 3 Factors
- The dimensions of the lumber
- The moisture content of the lumber?
- The density of the wood
The size or dimensions of the lumber is the most straightforward measurement. Accurately measuring board footage requires a tape measure or ruler.
Traditionally, lumber is measured in board feet. Here is a quick explanation of how to measure board feet.
The most common size lumber board according to Home Depot is 2 x 4.
Thus, for the sake of consistency, we use a standard 2x4x8 rough-sawn lumber plank in all of our examples.
Using our board footage calculator here, there are 6 board feet in a 2x4x8’ board.
Moisture Content Affects Wood Weight
However, board size is only one of the factors determining board weight. For example, a 2×4 x 8 lumber board of kiln dried sugar pine weighs significantly less than a 2x4x8, board of green white oak.
The 2×4 Pine is easily carried out of a Home Depot store by hand. The 2×4 green oak may require 2 people to safely carry. The weight difference is that substantial!
Lumber Density and Weight
Density is defined as mass per unit of volume. Density or Specific Gravity refers solely to the wood fiber of the lumber. Thus, water or moisture content is not considered in calculating wood density.
Wood densities range from a low of .3 for Paulownia wood to a high of 1.20 for Brazilian Kingwood!
In my experience as a career lumber professional, Wagner Meters are the best source for accurate specific gravity information by wood specie. You can check their extensive list of wood density by specie here.
1 Easy Way to Estimate Lumber Weight
In reality, most of us are not wood scientists needing exact measurements. Rather, we’re woodworkers trying to figure out if we can move some wood ourselves or if we need to call a friend or two for help.
Here is an easy way to roughly estimate the weight of a lumber board:
- Calculate or estimate the board footage of the timber.
- Is wood green (just fresh sawn) , air dried (been lying around a or kiln dry. Need moisture meter.
- Is it a softwood (pine, fir, spruce, etc)or hardwood (oak, maple, etc)
Here is a quick formula that calculates how much a board of air dried or kiln dried lumber weighs.
- Measure or estimate the board footage
- If the wood is air dried multiply by 1.3
- If the wood is kiln dried multiply by 1.0
- If it’s a hardwood multiply x 3
- If it’s a softwood multiply by 2
This calculation gives you a rough idea of wood weight. However, keep in mind that the average multipliers used cover a wide range of species. For example, both purpleheart and paulownia have the same hardwood multiplier.
Additionally, the formula adds 30% for water weight, when estimating air-dried lumber. This is a ballpark estimate. Air-dried wood may contain more or less water weight than our assumption here.
Thus, estimates are most accurate for woods with a specific gravity in the mean of the range.
For example:
- 2x4x8 air dried white oak
= 23.4 LB
- 2x4x8 kiln dried Poplar
= 18 LB
- 2x4x8 kiln dried Sugar Pine
= 12 LB
Another Way to Estimate Timber Weights
Here is another way to quickly and easily calculate approximate weight of a board. This is most useful when you can easily cut a sample. Additionally, if you have an unknown wood specie or lack access to a moisture meter, this method is acceptable.
- Cut a small portion of the board. Small enough to fit on a common bathroom or postage scale.
- Weigh the sample.
- Convert to LB’s/ 1 BF.
- Multiply by the BF of the board being estimated.
Unfortunately, that is only accurate if the moisture content of the sample piece is consistent throughout the board. Typically, the ends of a timber plank are drier (and thus lighter) than the interior portions of the lumber. This is due to the constant exposure of the end grain exposure to air flow. Accordingly, taking a small sample from the end may not accurately represent the average lumber weight.
Additionally, sometimes one the wood fiber is denser in one area of the board than another. We often see this phenomenon in punky swamp ash lumber. one end of the board, toward the submerged trunk of the log grew fast while the other didn’t. Thus, a board with low average weight may become one dense board and one ultralight board after being cut in half!
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