In the simplest terms, the modulus of elasticity (MOE) measures a wood’s stiffness, and is a good overall indicator of its strength.

Technically it’s a measurement of the ratio of stress placed upon the wood compared to the strain (deformation) that the wood exhibits along its length. MOE is expressed in pounds-force per square inch (lb_{f}/in^{2}) or gigapaschals (GPa). This number is given for wood that has been dried to a 12% moisture content, unless otherwise noted.

In practical terms, the number itself isn’t all that meaningful, but it becomes useful to use in comparison with other woods. For instance, Hickory is known to have excellent strength properties among domestic species in the US, and has a MOE of 2,160,000 lb_{f}/in^{2} (14.90 GPa). In comparison, Red Oak is another well-known wood used in cabinetry and furniture, and has a MOE of 1,820,000 lb_{f}/in^{2 }(12.50 GPa).

**Get the hard copy**

If you’re interested in getting all that makes *The Wood Database* unique distilled into a single, real-world resource, there’s the book that’s based on the website—the Amazon.com best-seller, **WOOD! Identifying and Using Hundreds of Woods Worldwide**. It contains many of the most popular articles found on this website, as well as hundreds of wood profiles—laid out with the same clarity and convenience of the website—packaged in a shop-friendly hardcover book.

Phillip CozensNovember 28, 2018 at 1:54 pmThe thing that folks miss here is that in using Youngs modulus with say metals the general assumption is that it is the same in tensile stress as in compressive stress. With wood this is definitely not the case. So in a wooden beam under load the modulus on the tension side of the beam is not the same as in the compression side. Hence difficult to analyse.

Don SchroederDecember 9, 2018 at 1:04 amThere are at least 2 reasons there are different published values for E for the same named wood and neither has to do with compression or tension of the wood fibers.

1. The Modulus of Elasticity published in many texts in the past was based on bending tests instead of opposing shear forces used in modern testing procedures. The bending test didn’t consider or compute either tension or compression in determining the value for E. The formula used the applied force, the span, the moment of inertia, and the deflection in a formula that is available in many older texts on wood strength.

2. Red Oak is a name applied to any of a group of related woods with a wide variety of wood properties. Some are exceptionally strong and some relatively weak but even within a specific species the values of E can vary significantly. Seeing a generic name being used for a variety of related woods isn’t uncommon.

Joe WillOctober 8, 2018 at 2:56 pmThis article says red oak “has a MOE of 1,820,000 lbf/in2 (12.50 GPa)”, but looking at the database page for red oak I find, “Elastic Modulus: 1,761,000 lbf/in2 (12.14 GPa)”

Why the discrepancy?

EricOctober 9, 2018 at 2:03 pmThe short answer is that I use the average of as many credible sources of data that I can find, and when this article was written, I was quoting from only one source, while the page on red oak has since been updated to reflect the most recent (averaged) data.

You can hear a little bit more of my rationale in determining values to list on the website in this longer video: https://www.youtube.com/watch?v=IfXW9Tw-3O0

Brad MackJuly 3, 2018 at 10:17 pmHang a weight from steel wire; say 1 pound. This weight acts under gravity to deform this wire along its length. The force is pure Tensile Force. intial length divided by change length gives strain. Young’s mod is then calculated based on the force (weight times acceleration due to gravity) and area of the wire. It can be clearly seen in the above woods database diagram, that a system of compression and tension is happening. The true lengthwise deformation would be given by Pythagoras. If the E value is to have any meaning, it would also mean that if we hung a weight directly off the end of a piece of wood, then the lengthwise deformation would be predicted. Alas, this wouldn’t occur. So these values are only helpful in comparing between woods. It is a Quasi-Young’s Modulus.

tk sarafJune 15, 2018 at 1:17 amThere is huge confusion in calculating MOE in Plywood please help us is there is any other method to calculate the said parameter Unit= N/mm2

GustafApril 27, 2018 at 1:04 amAwesome information and nice with everyone sharing comments trying to explain the modulus of elasticity. It makes it possible to read different explanations. This page is and will help me through my woodscience course. 5/5 Pine cones.

EduardFebruary 5, 2018 at 1:47 pmMOE is the ration between the stress and the (non-dimensional) relative elongation. If this ratio is 1/1000 (the material lengthens or shortens 1 mm for each meter), then the ratio gives 1000 more that stress, in the same units as yield or crush limit MOR.

Bernard KilBrideNovember 29, 2017 at 11:22 amHello

I am attempting to calculate whether a particular timber section (say C16 grade) will be strong enough, i.e. will not snap, under the wind load, and also the deflection at its tip. Can anyone help me with the formulae? i can work out the wind force and the bending moment at the posts base, just not how to determine its strength etc. i can do the maths once I know the formulae

Returnto SenderSeptember 8, 2017 at 3:24 pmI think you’d find that wood does bend easily given the same dimensions of steel. Try finding some rebar and a wooden dowel of the same diameter and length and compare the two.

StevenNovember 19, 2014 at 4:39 pmModulus elasticity is the ratio of stress to strain of a material in deflection (say in a beam) and is sometimes called ‘Young’s modulus’.

The higher the values of Young’s modulus the better.

Units: The units are ‘Pascals’ after the late French physicist – Blaise Pascal.

And GigaPascals (GPa) are often used. For example: The Modulus elacticity of Steel is 200GPa, and some softwood timbers are around 7GPa.

Steven McColl

Structural Engineer.

ufgDecember 10, 2015 at 3:28 am“better”

I presume this means better for structural engineering?

Higher value means more stiffness – which is not necessarily better for instrument making, probably archery and whatnot if the wood needs to bend a lot.

saarNovember 12, 2014 at 4:24 amI understand it much better now, thanks for taking the time to explain it :)

saarNovember 11, 2014 at 12:16 pmHey, I have a question about MOR and MOE. How can it be that the MOE > MOR in some woods? How can there be less force required to break something rather than bend it?

ejmeierNovember 11, 2014 at 2:29 pmAs I understand it, comparing MOE and MOR is like comparing apples and oranges: they’re really completely different types of measurements. (A fair comparison might be to compare MOR with Crushing Strength.)

MOR and crushing strength are simple measurements of the wood until failure occurs. Basically, how much force did it require to break the wood of a given size (usually standardized sizes are used).

MOE is a completely different animal in that it is a RATIO of two different measurements. It’s not only the force (stress) put on the wood, but also the amount that the wood has bent (strain). So it is stress DIVIDED by strain. So even if the stress does not exceed the theoretical MOR, if the strain is very low, you can come up with some very large MOE numbers due to a very small divisor.

For instance, 1000 / 2 = 500

but 1000 / .2 = 5000

or even 1000 / .02 = 50000