Production/capacity for a sawmill means an approximate production of sawn wood, lumber. (Some mills report actual production and some capacity).
In North America the volume is generally reported in board feet of sawn wood.
In Northern Europe the sawn wood volume is given in m3 of sawn wood.
In Central Europe the size is often given in m3 of round wood under the bark.
One board foot is theoretically equal to 1 inch x 12 inch x 12 inch or 2.360 liters, however the system was developed before the early 19th century when sawn wood was accounted for in a rough-green condition (a surfaced and dry 1 inch x 12 inch board is standardized to be .75 inches thick and 11.25 inches wide). Currently, the vast majority of North American sawn softwood is produced in a dry and surfaced (planed) condition and the actual volume contained in a board foot is significantly less in most situations (on average sawn softwood is considered to have an actual volume of 72% of the nominal volume). To convert a board foot to metric volume in m3 of sawn wood one have to take into consideration that in North America the real sawn dimension is less and in Europe, the volume reported in m3 is considered to be actual volume.
We have assumed the factor to be 1.7 m3 per Mfbm or 589 board feet per m3. A mill producing 100 000 Mfbm is thus reflected as 170 000 m3.
Hardwood lumber is considered to have 424 board feet of lumber per m3 as a result of the fact that very little is surfaced from the sawmill and in some cases the nominal volume is greater than the actual volume. We have assumed the factor to be 2.36 m3 per Mfbm of Hardwood. A mill producing 100 000 Mfbm will in m3 be 236 000 m3
When coverting from round wood volume to sawn wood we have assumed a yield of 50%. In practice, the yield for small logs can for example be 30% and for big logs 70% which means that our assumption shall be seen as an approximate.
For more information regarding conversion factors we recommend the UNECE/FAO report.
FOREST PRODUCTS CONVERSION FACTORS FOR THE UNECE REGION
UNECE/FAO Timber Section
Trade and Timber Division
United Nations Economic Commission for Europe
Palais des Nations
CH-1211 Geneva 10, Switzerland