Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

QUDT - Quantities, Units, Dimensions and dataTypes - public repository


This QUDT1 public repository contains the schema and vocabulary source files for the graphs making up the QUDT collection. It is probably the most convenient way for software developers to include the QUDT ontologies in their work, and is the most up-to-date. However, for those who prefer the linked data world, each QUDT graph is also available in both a versioned and an unversioned form on the website.

DOI reference for citations:

Here is the core design pattern of the QUDT ontology:

QUDT Triad Pattern

Here is the imports closure graph, so you can see which files you need to explicitly import, depending on your application:


Note that the default schema is expressed in SHACL. You can change this to use the OWL schema if you prefer, as documented here.

Our current plan is to deliver this material in even more powerful ways. The website now hosts an engine supporting SPARQL and GraphQL queries. Fully resolvable URIs at the graph and instance level are available online. Eventually we will also support resolvable class URIs as well. We are also creating a series of User Guides on the wiki for this repository.

We encourage you to get involved. If you have particular needs or see errors, please create an Issue and/or make changes or additions yourself (please see our Wiki for more detailed instructions, and specifically the Units Submission Guide if you would like to suggest additional units.) We are a volunteer-staffed effort, but we do have infrastructural expenses. Please consider making a DONATION.

Installation / Configuration instructions

The QUDT ontology is provided in two forms: OWL and SHACL. By default, the vocabularies are configured to use the SHACL schema. To configure it to use the OWL schema instead, just make the following single change in the file schema/shacl/SHEMA-FACADE_QUDT-v2.1.<release-number>.ttl. You can see in the imports closure diagram above how all the vocabularies import this single "facade" file to make it easy to switch the ontology.

Change this line:
  owl:imports <> ;  
  owl:imports <> ;

If you are using the tools from TopQuadrant, you should also change the comment line at the top of the same file:

Change this line:
# imports:
# imports:


Please see the New Features and Releases topic in the Discussions section for status updates.

1 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. Sponsorships are greatly appreciated! is a member of the World Wide Web Consortium (W3C)

Last updated by: Steve Ray (

Last updated: August 4, 2022


QUDT -Quantities, Units, Dimensions and dataTypes - public repository






Sponsor this project



No packages published