How Erosophia estimates your IELTS score

Why no website can reproduce the official band exactly

• For Listening and Reading, IELTS publishes only four reference points per test, given as averages: the exact number of correct answers needed for a band "will vary slightly from test version to test version" [1].
• On test day, Writing and Speaking are marked by certified examiners [1]. On Erosophia, an AI scores the answers; for Speaking, it only reads an automatic transcript.
• Even in the official test, the published standard error of measurement is 0.36 to 0.47 of a band in Listening and Reading, and 0.17 to 0.19 of a band on the overall band [2].

Listening and Reading

• Marking: as in the test, 40 questions per paper, 1 mark per correct answer, no negative marking [1]. Spelling and the word limit in the instructions count; capital letters do not.
• Conversion: the number of correct answers is converted to a band with a table that goes exactly through the official reference points; the values in between are interpolated by Erosophia. Reading has two tables, because General Training needs more correct answers than Academic for the same band [1].
• Practice by part: the result of a single part is scaled to 40 questions and shown as a rough guide only, because the parts get harder as the test goes on.

Official reference points (correct answers out of 40):

Writing

• Criteria: as in the test, each task is marked on four equally weighted criteria (Task Achievement or Task Response, Coherence and Cohesion, Lexical Resource, Grammatical Range and Accuracy), in whole bands [1]. The AI receives the official text of the band descriptors, updated in May 2023 [3], with the official rule: a script must fully fit the positive features of a level to be awarded it.
• Rules applied after the AI: so as not to rely on the AI's judgement alone, the site itself applies the limits set by the official descriptors [3]:
  • a response of 20 words or fewer, not counting text copied from the prompt, is rated Band 1 on all four criteria;
  • a response wholly unrelated to the topic is rated 1 for Task Achievement or Task Response;
  • a letter (General Training) that leaves out one of the bullet points is rated 4 at most for Task Achievement;
  • a report on a visual (Academic) with no overview is rated 5 at most, and 6 at most if the overview is not clear;
  • an essay with no paragraphs at all is rated 5 at most for Coherence and Cohesion.
  IELTS publishes no penalty scale for responses that are too short. Erosophia caps Task Achievement at 6 below the minimum word count (150 or 250), and at 5 below 80% of that minimum. In the free sample, Task 1 is shortened (at least 60 words): a text this short cannot show the range required for Band 9, so each criterion is rated 8 at most there.
• Writing band: each task's score is the average of its four criteria. Task 2 counts twice as much as Task 1 [4]. Intermediate rounding is not published; Erosophia rounds only once, to the nearest half band, at the end. A task left blank counts as 0.

Speaking

• Transcript: your recording is transcribed automatically; the AI then reads all your answers to the three parts and scores them on three official criteria: Fluency and Coherence, Lexical Resource, Grammatical Range and Accuracy, against the official band descriptors [5].
• Pronunciation: this is the fourth official criterion. The AI cannot hear it, so it does not score it. The Speaking band is the average of the other three criteria; in the test, all four count equally [1].
• Fixed rules: with no speech recorded at all, the band is 0, as for a candidate who does not take the test [5]; answers of only a few words are rated 2 at most. If the automatic transcription fails, the answer is left out and does not lower the score.
• Practice by part: the score of a single part is indicative; the AI is told that the other parts are missing.

Overall band

• As in the test, the overall band is the average of the four papers rounded to the nearest half band: an average ending in .25 goes up to the next half band, and one ending in .75 goes up to the next whole band (6.25 gives 6.5; 6.125 gives 6) [1].
• It is shown only when all four papers have been scored.
• CEFR level: IELTS publishes no exact equivalence. It places the C1 threshold between 6.5 and 7 and recognises 8.5 and above as C2 [6]. Erosophia does not show a CEFR level in its results.

How this scoring is checked

• Before each change, Erosophia has the site score a set of 51 reference answers: letters, reports on a graph, essays and full speaking tests from Band 4 to Band 8, the short answers of the free sample, plus edge cases (too short, off-topic, copied prompt, missing bullet point, silent recording…). These answers were first rated blind by three independent raters against the official descriptors; the raters are AI models distinct from the one that scores the site.
• At the last check, on 29 October 2026, the average gap between the site's band and the raters' band was 0 to 0.6 of a band depending on the task, and 24 edge cases out of 28 were scored correctly. On the free sample, the average gap was 0.25 to 0.5 of a band, and 8 edge cases out of 10 were scored correctly. The site still sometimes gave 9 to Band 7 letters and reports, and 8 to Band 8 essays that the raters scored 9.
• These raters are not certified IELTS examiners, and their ratings have not yet been compared with scripts marked by examiners. To check the scoring against real results, you can enter your official band, if you wish, on your "My progress — IELTS" page.

Official sources

1. IELTS, IELTS scoring in detail
2. IELTS, Test statistics (2024-2025)
3. IELTS, Writing Band Descriptors (updated May 2023)
4. IDP, IELTS Writing (Task 2 is worth twice as much as Task 1)
5. IELTS, Speaking Band Descriptors
6. IELTS, IELTS and the CEFR

IELTS® and the IELTS logos are registered trade marks. IELTS is jointly owned by the British Council, IDP IELTS and Cambridge University Press & Assessment; Erosophia is not affiliated with any of them. Page updated on 29 October 2026.