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5908 Measurement System Basics: SI & U.S. Customary Units for Regulatory Officials

This 1.5-hour webinar will introduce the measurement systems commonly used in the United States, including the International System of Units (SI) and U.S. Customary systems (e.g., Avoirdupois, Apothecary, and Troy units).

This session is ideal for participants who would like to become more familiar with measurement systems used in field, laboratory, and manufacturing activities.  Accurately expressing measurement quantities in written communications is critical. Writing style best practices, unit symbols and prefixes usage, and error recognition will be addressed.

Learning Objectives

At the end of this session, using your notes, you will be able to:

  • DEFINE the terms legal unit of measurement and legal metrology.
  • IDENTIFY systems of measurement units used in the United States.
  • LIST official sources of measurement system information.
  • DISCOVER common unit symbol writing errors.

Materials & Supplies






Minimum Requirements

Successful Completion includes full attendance and participation in all session activities and discussions.  Session participants will receive a Certificate of Attendance (which does not include participant names or CEUs) delivered by email after the session.  Attendance is recorded in the unofficial transcript, which is available in the OWM Contacts System.


Weights and Measures field and program officials, state laboratory metrologists, and others who have responsibilities for conducting regulatory and enforcement activities.

Registration Fee

There is currently no registration fee for this webinar.


Elizabeth Benham
Phone: (301) 975-3690
Email: elizabeth.benham [at] (elizabeth[dot]benham[at]nist[dot]gov)

Technology Requirements

The webinar will be a live stream, so participants must have a constant connection during the webinar (hard-wired is preferred).
System requirements for Webex services:

Review these system requirements to verify that you can use the Webex App on your computer, mobile device, or web browser.  Other factors may also influence the performance of the Webex App, for example, network connectivity or other applications on your devices. 

  • Windows PCs:
    • Windows 10 and later. Make sure your drivers are up to date.
    • Intel Dual-Core CPU 2.XX GHz or AMD processor (4 GB of RAM minimum recommended).
    • Some features require additional system requirements:
      • Reactions in a scheduled Webex Meeting or Personal Room meeting.
        • Operating System—Windows 10 version 10.0.17763 or later
        • Processor—four physical cores or more
        • Memory—4 GB or more of RAM
  • Mac:
    • OS X 10.7.5 or later
    • 2GB of memory
    • 8.8GB of available storage
    • Some features require an Apple ID; terms apply.
    • Some features require a compatible Internet service provider; fees may apply.
  • Web Browsers:
    • On computers running Windows, Mac, or Linux, ensure you have the latest release of one of these browsers:
      • Google Chrome,
      • Mozilla Firefox,
      • Apple Safari, and
      • Microsoft Edge.
  • Linux recommended minimum system requirements. 
    • Core requirements: Intel Dual-Core CPU 2.XX GHz or AMD processor (4 GB of RAM minimum recommended)
    • Display Protocols: x11 and Wayland.
    • Desktop environment/Window Manager: GNOME/Mutter and KDE/KWin are recommended.
Created February 7, 2024, Updated April 1, 2024