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5850 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 the session activities and discussions.  Session participants will receive a Certificate of Attendance (does not include participant name or CEUs) delivered by email after the session.  Attendance is recorded in the unofficial transcript, 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.


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).
1. Operating System (browser) configurations:

  • Windows
    • Windows 10, 8.1 (32-bit/64-bit), Windows 7 (32-bit/64-bit)
    • Microsoft Internet Explorer 11 or later, Windows Edge browser, Mozilla Firefox, and Google Chrome
    • For HTML Client - Google Chrome (v70.0 & above), Mozilla Firefox (v65.0 & above), and Edge (v42.0 & above)
  • Mac OS
    • Mac OS X 10.12, 10.13 and 10.14
    • Mozilla Firefox, Apple Safari, Google Chrome
    • For HTML Client - Google Chrome (v70.0 & above), Apple Safari (v12.0 & above), and  Mozilla Firefox (v65.0 & above)
  • Linux
    • Ubuntu 16.04; Red Hat Enterprise Linux 6
    • No application support is available for Linux. Users on Linux can attend meetings in a browser.
    • Google Chrome, Adobe Flash Player 23.0

2. Mobile

  • The Adobe Connect app for iOS and Android requires Adobe Connect Server version 8.2 or later
  • Some features may not be enabled in all Adobe Connect meetings if one is using an Adobe Connect Server older than version 9.4.2 (required for Custom pods)
  • Google Android 4.4 or later
  • Apple iOS: iOS 8.1.2 or later

3. Media players

  • In order to access the event, you must have, at a minimum, Adobe® Flash® Player 13 or higher installed on your computer. Please visit to download the Flash Player.

4.  International Phone Calls

  • Before the webinar – Participants are responsible for verifying and testing that international calling is enabled on any telephone extension that will be used during the webinar.  Some organizations permit only domestic calls, which may restrict the participant from making an international call to the OWM toll free number.  A request to enable international call services may be necessary.  Failing to test the international phone service could prevent participation in the webinar.

5. Optional: If you have never attended an Adobe Connect meeting before:

* Adobe, the Adobe logo, Acrobat and Adobe Connect are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries.


NIST Office of Weights and Measures

Created December 6, 2022, Updated March 13, 2023