What are the different English proficiency levels based on?

The Common European Framework of Reference for Languages is an internationally accepted standard for describing levels of language ability.

The Common European Framework of Reference for Languages (abbreviated as CEFR) is an internationally accepted standard for describing levels of language ability. Measures of proficiency are based receptive skills (listening and reading) and productive skills (speaking and writing), as well as the ability to use grammar and vocabulary at the appropriate level. These levels of ability are used as the basis for the development of course books and for English proficiency tests.

In terms of the CEFR framework, learners are divided into six main proficiency levels:

A1 – Breakthrough

A2 – Waystage

B1 – Threshold

B2 – Vantage

C1 – Effective operational proficiency

C2 – Mastery

Detailed descriptions are available of what learners are supposed to be able to do at each level. For example:

A1 – Can understand and use familiar everyday expressions; can interact in a simple way provided the other person talks slowly and clearly and is prepared to help.

B2 – Can understand the main ideas of complex text on both concrete and abstract topics, including technical discussions in specific fields.

From: https://www.english-efl.com/english-language-levels/

In the introduction to the Beginner course book of the LIFE series by National Geographic Learning, Mike Sayer (2021) says that the CEFR “is designed as a set of common reference points” that provide teachers and students with shared learning objectives. “The LIFE series has a communicative approach with an emphasis on language learning in real life contexts and on producing language in a broad range of speaking and writing situations.” The LIFE series therefore aims to provide English students with the ability to communicate in a range of realistic situations. The course books cover the various outcomes for the CEFR levels, and so correspond to each CEFR level as follows: LIFE Beginner – A1 (Breakthrough) LIFE Elementary – A2 (Waystage) LIFE Pre-intermediate – B1 (Threshold) LIFE Intermediate – B1 + B2 (Threshold & Vantage) LIFE Upper intermediate – B2 (Vantage) LIFE Advanced – C1 (Effective operational efficiency)

Sources: https://en.wikipedia.org/wiki/Common_European_Framework_of_Reference_for_Languages https://www.olesentuition.co.uk/single-post/what-is-the-difference-between-a1-a2-b1-etc https://www.cambridgeenglish.org/exams-and-tests/cefr/ https://www.ngllife.com/content/cefr-correlations