The Rural Technology Initiative ceased operations in 2011. This site is maintained as an archive of works from RTI collaborators from 2000 to 2011 and is no longer updated. RTI's successor and remaining staff can be found at

Search the RTI Website
Click to go to the Precision Forestry Cooperative website
Click to go to the RTI Home page
Click to go to the About RTI page
Click to go to the RTI Projects page
Click to go to the RTI Publications page
Click to go to the RTI Tools page
Click to go to the RTI Geographic Information Systems page
Click to go to the RTI Streaming Video Directory
Click to go to the RTI Training page
Click to go to the RTI Contacts page
Click to go to the RTI Image Archive
Click to go to the RTI Site Map
Click to go to the RTI Links page

Forest Products Measurements and Conversion Factors


With Special Emphasis on the U.S. Pacific Northwest

Copyright © 1994 by the College of Forest Resources, University of Washington
Printed in the United States of America

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photography, recording, or any information storage or retrieval system, without permission in writing from the publisher, the College of Forest Resources.

Additional copies of this book may be purchased from the University of Washington Institute of Forest Resources, AR-10, Seattle, Washington 98195.

Editing and Design: Leila Charbonneau
Word Processing: Margaret Lahde
Shirley Verzosa

Library of Congress Cataloging-in-Publication Data

Briggs, David George.
Forest products measurements and conversion factors : with special emphasis on the U.S. Pacific Northwest / David Briggs.
p. cm. - (Institute of Forest Resources contribution ; no. 75)
Includes bibliographical references (p. ) and index.
1. Forest products-Northwest, Pacific-Measurement. 2. Forest products-Standards-Northwest, Pacific. I. Title. II. Series: Contribution (University of Washington. Institute of Forest Resources) ; no. 75.
TS806.P33B75 1994


1. Basic Wood Properties: (For a printout or download, go to Chapter 1 pdf)

2. Measurement of Logs: (For a printout or download, go to Chapter 2 pdf)

3. Stacked Roundwood, Preservative-Treated Products, and Construction Logs:
(For a printout or download, go to Chapter 3 pdf)

4. Lumber
: (For a printout or download, go to Chapter 4 pdf)

5. Veneer and Plywood
: (For a printout or download, go to Chapter 5 pdf)

6. Nonveneer Panel Products: Particleboard, Hardboard, Medium Density Fiberboard, OSB/Waferboard, and Insulation Board: (For a printout or download, go to Chapter 6 pdf)

7. Chips, Sawdust, Planer Shavings, Bark, and Hog Fuel: (For a printout or download, go to Chapter 7 pdf)

8. Pulp and Paper: (For a printout or download, go to Chapter 8 pdf)

9. Energy: (For a printout or download, go to Chapter 9 pdf)

10. Shingles and Shakes: (For a printout or download, go to Chapter 10 pdf)

11. Biomass and Utilization of Trees: (For a printout or download, go to Chapter 11 pdf)

Appendix 1. Conversions Between Imperial and Metric Measures: (For a printout or download, go to Appendix 1 pdf)

Appendix 2. Conversion Factors for Wood Products: (For a printout or download, go to Appendix 2 pdf)

Appendix 3. Board Foot Log Rules: (For a printout or download, go to Appendix 3 pdf)

Appendix 4. Scientific and Common Names of Tree Species: (For a printout or download, go to Appendix 4 pdf)

Appendix 5. Associations and Grading Agencies: (For a printout or download, go to Appendix 5 pdf)

Glossary: (For a printout or download, go to Glossary pdf)

References: (For a printout or download, go to References pdf)



Completion of this book would not have been possible without the tremendous education and support given me by many practitioners in the forest products industry and the numerous queries I have received from people confused or troubled by some measurement or conversion problem. This is an educational process that is ongoing. The following were especially helpful in aiding with preparation and review of various chapters:

Craig Adair, American Plywood Association
David Anderson, Graduate Research Assistant
Jack Eddy, Red Cedar Shingle and Handsplit Shake Bureau
Tom Fahey, USFS Pacific Northwest Research Station
Don Flora, USFS Pacific Northwest Research Station
Rick Gustafson, University of Washington
Denny Hill, Graduate Research Assistant
Kevin Hodgson, University of Washington
Robert Keller, Weyerhaeuser Company
Bruce Lines, Wyckoff Company
Les Lonning, L.D. McFarland Company
Tom Maloney, Washington State University
Bob Netro, L.D. McFarland Company
George Sleet, American Plywood Association
Ed Williston, Ed Williston Associates, Inc.
Sue Willits, USFS Pacific Northwest Research Station
Gerry Willits, U.S. Bureau of Land Management
Ken Wilson, Weyerhaeuser Company

My thanks also go to Tom Snellgrove, former Project Leader of the Timber Quality Research Unit at the U.S. Forest Service Pacific Northwest Research Station, who originally suggested that I do this book.
Development of this publication was supported by the U.S. Forest Service Pacific Northwest Research Station Project 88-325, the University of Washington Center for International Trade in Forest Products (CINTRAFOR), the McIntire-Stennis Cooperative Forestry Research Program, and the University of Washington College of Forest Resources.

David Briggs


Understanding forest products measurements is important to anyone in the forest products industry. Converting volume, area, lineal, or weight measurements between the metric and Imperial systems is not as simple or straightforward as it would seem. Incorrect, obsolete, and ambiguous conversion factors can be very misleading and may result in large errors. Some reasons for this are:

1. Lack of standardization as to how measurements are taken and recorded. For example, logs may have diameter taken at one end, both ends, or at midlength; the measure may be inside or outside bark, and may be recorded to the nearest tenth, nearest inch or centimeter, or with the fraction dropped.

2. Even if the same measurements are recorded, they may be entered into different formulas that yield different results. Various cubic log volume formulas yield different results even when the same log measurements are used. Often, log scaling systems differ both in the way measurements are taken and in the formula used.

3. The units for expressing volume or weight are often different and may not be clearly defined. Log volume may be expressed in cubic feet, cubic meters, board feet, koku, and so forth. A ton of chips may be wet or bone dry and may be a short ton, long ton, or metric tonne. Chips are also expressed as units and bone-dry units.

4. Even if the same unit of measurement is used, it may not represent the same quantity. A good example is the difference between a board foot in log scaling and a board foot in tallying lumber at a sawmill.

5. Correct conversion factors for some products, such as logs and lumber, vary with piece size.

6. Wood is variable. Wood density-the measure of mass of wood per unit volume-varies between species, between trees of the same species, and between parts of the same tree. Wood moisture content can vary from a few percent to more than half the weight of a piece. Since wood shrinks and swells as moisture content changes, these changes affect volume as well as weight. Many wood product measurements and conversion factors that are reported are ambiguous because no indication of such conditions is given.

While this book primarily focuses on forest products in the Pacific Northwest, several national and foreign systems are included because of the rapid globalization of markets. Because many readers may be relatively new to the industry and its terminology, a glossary is provided and descriptive background on the philosophy and assumptions that underlie formulas and measurement systems is presented. Procedures and illustrative examples are emphasized to encourage the reader to gather and use local information rather than rely on tables of averages. With the ready availability of computers and software packages, the focus on procedures is appropriate to enable readers to develop software to perform calculations they need. Tabulated species and regional averages are also presented. These values can be used as a rough check on calculations or as an approximation if local data are not available. The reader should be cautioned that tabled averages may be based on limited samples, so conversion factors calculated from these tables may differ substantially from the local reality.
Although the examples were taken from actual situations, they should not be regarded as representative of the current forest resource or average industry practice. They were chosen to illustrate and reinforce the calculation methods, to provide insights on how systems attempting to measure the same product vary, and why some are less consistent or more biased than others.
The appendixes provide tables of standard conversion between Imperial and metric measures, conversion factors used by the U.S. Forest Service in its latest assessment of the U.S. timber situation (Haynes 1990), some examples of board foot log rules, common and scientific names of U.S. tree species, and names of industry associations for products discussed in this book.
Information on the physical and mechanical properties of commercially important species, along with descriptions of products, processes, and grades, can be found in the Wood Handbook (USFS 1987), which is recommended as a companion to this volume. It is available through the U.S. Government Printing Office.
Unlike previous editions, this version does not contain forestry yield tables, site curves, and so forth. This and other forestry information is well covered in Log Scaling and Timber Cruising, by J.F. Bell and J.R. Dilworth, available through the Oregon State University Press, Corvallis.
Readers are encouraged to send the author descriptions of measurement systems and conversion factors not covered in this edition. These inputs will be valuable in expanding the scope of future editions to include more foreign country systems as the forest products industry continues its globalizing trend.

School of Environmental and Forest Sciences
USDA Forest Service State & Private Forestry
WSU Cooperative Extension
The Rural Technology Home Page is provided by the College of Forest Resources. For more information, please contact the Rural Technology Initiative, University of Washington Box 352100 Seattle, WA 98195, (206) 543-0827. © 2000-2004, University of Washington, Rural Technology Initiative, including all photographs and images unless otherwise noted. To view the privacy policy, click here.
Last Updated 10/13/2022 12:34:03 PM