Lumber Shrinkage Estimator


This program is designed to estimate the shrinkage in standard Western lumber products based on changes in the moisture content of the lumber.

Select the species group, initial moisture content, final moisture content and the size of the lumber to calculate the amount of shrinkage. An additional species group selection is available to allow you to compare products of different Western species.

Since dimensional changes in lumber products can be affected by other variables such as temperature, time in service or humidity conditions, the sizes calculated here should be considered as estimates. Shrinkage will also vary depending on method of sawing (for example, flat sawn vs. quartersawn lumber). The program assumes shrinkage occurs tangentially to the growth rings (the greatest directional form of shrinkage in wood}. For additional information on dimensional stability order the publication Dimensional Stability (TG-3) from WWPA.

The Lumber Shrinkage Estimator was developed by Oregon State University in cooperation with Western Wood Products Association. Programming by Scott Leavengood, OSU Extension Faculty, web site:

Condition of Seasoning:
There are three levels of standard condition of seasoning at the time of surfacing at mills:
S-GRN =over 19% moisture content (unseasoned)
S-DRY, KD or KD-HT = 19% maximum moisture content
MC15 or KD15 = 15% maximum moisture content 

Shrinkage %:
This value reflects the total shrinkage that would be expected if the piece were to shrink from green (saturated with moisture) to 0% moisture content (green to ovendry).


Western Wood Products Association (WWPA) provides the Lumber Shrinkage Estimator "as is" without warranty of any kind, either express or implied. Telephone support for the installation and operation of the Lumber Shrinkage Estimator is not available from WWPA.

WWPA and Oregon State University provides this program for informational purposes only and does not represent or warrant that any information provided in this program is correct, complete or up to date. WWPA and Oregon State University, may change or delete information in this program without notice at any time.

The WWPA Lumber Shrinkage Estimator may not be altered, modified or sold for commercial purposes. WWPA and Oregon State University makes no warranties expressed or implied concerning this product. In no event will WWPA and Oregon State University be liable for indirect, incidental, special or consequential damages, whether in contract, tort, strict liability or under any other legal theory arising from use of the WWPA Lumber Shrinkage Estimator.


WWPA Lumber Shrinkage Estimator