What you need to know about the upcoming survey foot change

On January 1, 2023, the international survey foot is slated to officially replace the U.S. survey foot, in an effort by the National Ocean Service (NOS) and the National Oceanic and Atmospheric Administration (NOAA) to provide uniformity and eliminate ambiguity when measuring length.

Trimble tape measureThe difference between the U.S. survey foot and international survey foot methods seems small at only two parts per million; however, this difference adds up over long distances and will be noticeable to surveyors and civil engineers using modern measurement techniques. ABC News shares perspective on the difference: The international foot is the smaller one — adding about an eighth of an inch of difference when measuring a mile. That means the United States is 28.3 feet wider when measured using the international foot instead of the U.S. survey foot.

This change marks a new era for many land surveyors, engineers, federal, state and local government officials, as well as businesses in the surveying and mapping profession, so Trimble aggregated the following resources to illuminate the U.S. survey foot and international survey foot measurements, the reasoning for the change, and what to expect on January 1, 2023.

  • The National Institute of Standards and Technology (NIST) and the National Geodetic Survey (NGS) recently announced a 90-day delay of the decision to deprecate the U.S. Survey Foot to give more time for the review and analysis period to address public comments.
  • This Surveyor Says! podcast from the National Society of Professional Surveyors (NSPS) features insights on the need for, and cost of, the change – from national geodesist and State Plane Coordinate System 2022 Project Manager for NGS, Dr. Michael Dennis.
  • This intermediate-level NGS webinar – Putting the Best “Foot” Forward: Ending the Era of the U.S. Survey Foot – also led by Dr. Dennis, offers a tutorial on the need for national uniformity for accurate length measurement.
  • This NIST “Ending the Era of the U.S. Survey Foot” summary webpage links to FAQs and other resources to further educate and support those affected by the change.
  • This ABC News article offers a less-technical general overview of the change, and reasoning behind it.
  • This NOAA video production offers a visual tutorial on the difference in measurement between the U.S. survey foot and the international survey foot over longer distances.
  • This POB Online article details insights of the upcoming U.S. survey foot to international survey foot change from the perspective of a professional land surveyor. Note: POB Online article access (beyond three complimentary views per month) requires a subscription.

Trimble customers should expect a smooth transition, as the international survey foot and U.S. survey foot are already standard measurement unit options in our products.


About the Author

Trimble-Geospatial
Trimble Geospatial

Trimble Geospatial provides Land Surveying, GIS, Scanning, Mobile Mapping, Remote Sensing, Photogrammetry and Forensics professionals with industry leading hardware and software solutions.