Can ChatGPT score my IELTS essay accurately?
No. General-purpose AI marks IELTS essays generously, because it has no fixed reference for where the band boundaries sit. We know because we measured it on our own scorer: it ran 0.29 bands high, we published that, and we corrected it.
Check my essay freeWhat we actually measured
We scored a fixed set of reference scripts four times over, holding out a different quarter of them each time so no script was ever marked against itself. Without a calibrated reference ladder in the prompt, our scorer came out 0.29 bands high on average, with a 95% confidence interval of +0.05 to +0.52. That interval excludes zero, which is the statistical way of saying the generosity was real and not noise.
Half a band matters. It is the difference between a 6.5 and a 7, and a 7 is what most universities and immigration streams ask for. A tool that tells you that you are ready when you are not has not been kind to you.
Showing the model a ladder of already-marked scripts fixed it. The measured bias is now 0.05 bands, with an interval that includes zero, which is as close to no systematic lean as this sample size can demonstrate.
General-purpose AI against a dedicated scorer
| Capability | General AI assistant | BandNine.ai |
|---|---|---|
| Marks against the four official criteria | Only if you paste the descriptors in yourself | Every script, every time |
| Same essay, same band on resubmission | Often differs between attempts | Identical, by design |
| Accuracy measured against a fixed reference set | Not measured | Re-measured weekly and published |
| Deviation published with sample size and interval | No | Yes, including the bad weeks |
| Sentence-level errors identified in your own text | Tends to rewrite the whole passage | Highlights the exact lines |
| Marked by certified IELTS examiners | No | No, and we say so |
The last row is in the table on purpose. Our reference set is in-house, descriptor-labelled, and no script in it has been marked by a certified examiner. Any comparison table that gives its own product a clean sweep is selling you something.
Across 24 scripts, measured 2026-08-23. At this sample size the interval is wide, so read it as an order of magnitude rather than a precise figure. The methodology, the limitations and every previous run are on the quality page.
Who marked the reference scripts
The band descriptors were applied by qualified teachers, not generated by the model being tested. Delta is the Cambridge Diploma in Teaching English to Speakers of Other Languages, the qualification above CELTA. Between them they have 13 years of IELTS classroom experience.
Frequently asked questions
Can ChatGPT give me an accurate IELTS band score?+
It can give you a band, and it will usually be too high. A general assistant has no fixed reference for where the band boundaries sit, so it applies its own, and its own is generous. It is genuinely useful for grammar and for ideas. It is not a marker.
Why does AI overrate IELTS essays?+
Two reasons. It is trained to be agreeable, and it has no calibrated scale to mark against. We measured this on our own scorer: without a reference ladder it ran 0.29 bands high on average, with a 95% confidence interval of +0.05 to +0.52, which excludes zero. Adding a ladder of already-marked scripts removed it.
Will ChatGPT give me the same band twice for the same essay?+
Usually not. Ask twice and you can get two different bands, which makes it impossible to tell progress from noise. Our scoring is deterministic by design: submit the same script again and you get the identical result, and you can verify that yourself.
How do I know your scoring is any better?+
Check it. We re-measure against a fixed reference set and publish the deviation with its sample size and confidence interval, including the weeks it gets worse. The methodology and the limitations are on our quality page. We are not aware of another AI IELTS scorer that publishes a measured deviation figure, though at least one publishes an accuracy page.
Is your reference set marked by real IELTS examiners?+
No, and we say so on the page. The scripts are labelled in house against the public band descriptors. That means the figure measures agreement with our own labelling, not with a certified examiner. Getting examiner-marked scripts is the single biggest improvement available to us and we are honest that we do not have them yet.
See your band in about two seconds.
Marked against the four official criteria, with the exact lines that cost you marks. Free, no signup.
Check my essay free