QUDT.org is a 501(c)(3) not-for-profit organization founded to provide semantic specifications for units of measure, quantity kind, dimensions and data types.   QUDT is an advocate for the development and implementation of standards to quantify data expressed in RDF and JSON.   Our mission is to improve interoperability of data and the specification of information structures through industry standards for Units of Measure, Quantity Kinds, Dimensions and Data Types.

QUDT.org is a member of the World Wide Web Consortium (W3C)

Why QUDT.org

QUDT.org exists to make the QUDT Ontologies, derived models and vocabularies available to the public. Originally, QUDT models were developed for the NASA Exploration Initiatives Ontology Models (NExIOM) project, a Constellation Program initiative at the AMES Research Center (ARC).

Current Activities

QUDT.org is in the process of publishing release 2.1 of QUDT which has ontologies for Units of Measure, Quantity Kinds, Dimensions and Types, available under a Creative Commons Attribution 4.0 International License (CC BY 4.0). Attribution should be made to QUDT.org.   The current catalog can be found at QUDT Catalog Release 2.1. With this release, we have consolidated the unit and quantity kind vocabularies so that specific instances are easier to find, but there is still more considation to do. QUDT Catalog Release 2.0 is still available for reference.

Version 1.1 of the QUDT ontologies may be downloaded from the QUDT Catalog Release 1.1, which can also be accessed from LinkedModel.org.   The catalog covers many domains of units and quantities and is being published incrementally.

If you wish to participate in reviewing this work please email manager at qudt.org.


QUDT is governed by a board of directors from different organizations.