Introduction
Starting in 2025, COUNTER Metrics introduced a new version of its standard, COUNTER 5.1. This article summarizes the key differences between COUNTER 5.1 and its predecessor, COUNTER 5, highlighting updates in data types, access types, reporting structures, and authentication methods.
What’s New in COUNTER 5.1
Expanded Data Types
- The "Multimedia" category has been refined into more specific types: Audiovisual, Image, Interactive_Resource, Multimedia, and Sound.
- COUNTER 5.1 also added new data types for other materials, including Conference, Reference_Work, and Standard.
Changes to Access_Type
- To better handle free content, Access_Type categories were updated:
- Previously: Controlled, OA_Gold
- Now (COUNTER 5.1): Controlled, Open, Free to Read
- The meaning of each Access_Type was clarified to reflect the item's status at the moment of access:
- Controlled: Material only available to authorized users (e.g., registered members or subscribers) — content behind a paywall
- Open: Content freely available to everyone with no end date, regardless of license
- Free to Read: Materials temporarily available to everyone with an end date (e.g., promotional temporary access)
Structural Updates in Reports
Section_Type was removed from the Title Report.- Book usage calculation has changed due to the move to item-level reporting. While Title metrics are not affected, the Item_Request and Item_Investigation metrics are different due to the revised counting methods for the items (book chapters).
For example, Unique_Item_Requests will often be higher in COUNTER 5.1 than in COUNTER 5 for the same book title due to counting usage for each chapter when the whole book is downloaded.
SUSHI Renaming & API Updates
- SUSHI has been officially renamed to COUNTER API; nevertheless, the term SUSHI is still commonly used.
- The API endpoint URL changed to include the /r51/ appended to the unmodified COUNTER 5 URL path.
- Credentials & Data Hosts:
- Existing Data Providers: Existing credentials stay the same in most cases, though some providers may introduce API keys to improve security (such as replacing IP-based authentication).
- Host Migration: When a publisher switches to a new data host during the transition, completely new credentials will probably be required.
Differences Between COUNTER 5 and COUNTER 5.1 Data
The differences between COUNTER 5 and COUNTER 5.1 data were expected to be relatively minor, though some trends emerged. The most significant are:
- Increase of the Book Item usage due to the modified counting methodology (see the paragraph "Book usage calculation..." for more detail)
- Shifts between Data_Types and Access_Types, more to the latter in CELUS KB article: Where is OA_Gold in COUNTER 5.1?
As most publishers already adopted COUNTER 5.1, further trends and insights have emerged, helping to refine comparisons between COUNTER 5 and COUNTER 5.1 datasets.
By understanding these changes, libraries, publishers, and institutions can better adapt to COUNTER 5.1 and ensure accurate and meaningful usage reporting.
In CELUS, analysis of the transition impact can be efficiently done in CELUS Reporting How to Compare COUNTER 5 and COUNTER 5.1 Data in CELUS or CELUS Data Hub.
Additional resources:
CELUS Knowledge Base:
COUNTER METRICS:
