How Accurate Is an AI IELTS Writing Checker? We Tested Ours Against Examiner Bands

The short answer

On 23 published sample scripts marked by IELTS examiners, the ieltswrites AI was on average 1.04 bands away from the examiner band. It was within half a band on 34% of scores and within one band on 72%.

It ranked essays well, with a correlation of 0.86 between its average band and the examiner band for each script, but it scored too low overall. The average gap was -0.84 of a band, and the gap grew as the writing improved. Treat a result of 5.5 or above as possibly too low. This is a small first test, not a validation.

Results by examiner band

Each script was scored up to three times, giving 67 scores. A negative gap means the AI scored below the examiner.

• Examiner band below 6 (9 scripts, 26 scores): average error 0.37, average gap +0.13, within half a band 88%, within one band 100%.
• Examiner band 6 to 7 (10 scripts, 29 scores): average error 1.17, average gap -1.17, within half a band 0%, within one band 76%.
• Examiner band 7.5 and above (4 scripts, 12 scores): average error 2.17, average gap -2.17, within half a band 0%, within one band 0%. For example, an examiner band of 9 received 6.5 to 7, and a band of 8 received 5.5 to 6.
• By task: Task 1 had an average error of 1.03 on 13 scripts, and Task 2 had 1.05 on 10 scripts.
• Repeat runs were stable. The same script differed by an average of 0.13 of a band between its highest and lowest score, so being consistent did not make the band correct.

How we tested it

We ran the test on 2 November 2026 with the model and prompt used in production at the time (deepseek-flash, prompt v8-2026-10-30). The prompt was not tuned on these scripts.

• Scripts: 12 Academic and 11 General Training responses from IELTS sample documents titled Sample Candidate Writing Scripts and Examiner Comments, with bands from 3 to 9. The documents say the scripts were marked by trained and certificated IELTS examiners.
• Transcription: the responses are handwritten scans, so an AI model transcribed them word for word, keeping the candidates' errors. About 95 of 5,314 words were marked as uncertain, and no person checked the transcripts line by line.
• Questions: we used the matching sample tasks. For Academic Task 1 we also supplied a text description of the visual, with approximate values read from the chart.
• Comparison: the checker's overall band for a task against the examiner's band for that task. The documents give one band per task, so we could not compare the four criteria separately.
• Failures: 2 of 69 attempts produced an invalid report and were left out. The site would retry these automatically.

Limits of this test

• The sample is small. Only 4 scripts are at band 7.5 or above, and only one is at band 9.
• The sample documents say the answers should not be regarded as definitive examples of any band score.
• The scripts are older handwritten responses, while most users of the site type their essays. Transcription errors may also have affected some bands.
• These figures describe this model and prompt only, and they will change when either changes.
• These results cannot be compared directly with other tools' figures, because those tests used different essays and reference bands.

What this means for your practice

• Do not use a single AI band to decide whether you are ready to book the test.
• If you already write well, expect the band to be conservative. On this test, examiner bands from 6 to 7 usually came back about a band lower.
• Use the line-by-line corrections and criterion notes to find repeated errors, and compare your essays over time with the same tool.
• Before an important decision, have a qualified teacher or examiner mark a sample of your writing.

Common questions

• How accurate is the ieltswrites band score? On 23 examiner-marked sample scripts, the average error was 1.04 bands, with 34% of scores within half a band and 72% within one band.
• Does ieltswrites score too high or too low? Too low for stronger writing. It was close below band 6, about 1.2 bands low from band 6 to 7, and about 2.2 bands low at band 7.5 and above.
• Are AI IELTS Writing checkers accurate enough to predict my exam band? Not from one essay. Use them to find errors and track trends, and treat any band as an estimate.

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