IELTSVegaAI IELTS Writing checkers: how they score, and how to actually use one
How AI essay scoring works against the four IELTS Writing criteria, where it is reliable, where it is not, and the routine that turns feedback into a band.
The hardest part of preparing for IELTS Writing alone has always been that you cannot mark your own essay. You wrote it, so it makes sense to you, and the specific reasons an examiner would cap it at 6.5 are invisible from the inside. AI scoring solves that, but only if you understand what it is doing and use the output properly.
Here is how these tools work, what they are reliable at, what they are not, and the review routine that converts feedback into an actual band increase.
What the four criteria actually measure
- Task Response (Task Achievement in Task 1): did you answer the whole question, take a clear position, and develop your ideas with support? This is where most 6.5s are capped.
- Coherence and Cohesion: is it logically organised into paragraphs, with ideas linked naturally rather than by a list of connectives?
- Lexical Resource: is your vocabulary varied, precise and appropriate? Not rare words. Precise ones, used correctly.
- Grammatical Range and Accuracy: do you use a range of structures, including complex ones, with control? Range and accuracy both count, so error-free simple sentences cap out around Band 6.
- Your Writing band is derived from all four, and in Task 2 the essay carries roughly twice the weight of Task 1.
How AI scoring works
A well-built checker does not pattern-match on length or count linking words. It assesses your text against each descriptor separately and produces a band per criterion, then combines them the way the marking scheme does.
That per-criterion structure is the whole point. It is also the fastest way to judge whether a checker is any good: if it returns one number with generic advice, it is not modelling the marking scheme, it is guessing.
Where AI scoring is reliable
- Grammatical Range and Accuracy. Error detection and structural variety are exactly what language models are good at, and this is the most reliable of the four.
- Lexical Resource. Repetition, imprecise collocation and register mismatches are detected well.
- Coherence and Cohesion. Paragraph structure, missing topic sentences and mechanical linking are picked up reliably.
- Consistency. An AI marks your twentieth essay to the same standard as your first, which no tired human reliably does, and consistency is what makes progress measurable.
Where to be careful
Task Response is the hardest criterion to automate, because it requires judging whether an argument genuinely addresses the question and whether the support is relevant. Good models handle it well; weak ones reward length and confident phrasing.
There is also a systematic thing to watch: AI scoring can be slightly generous with an essay that is well-organised but empty, because structure is easy to see and substance is not. If your feedback consistently praises structure and never questions your ideas, treat your Task Response band as the least certain of the four.
And a floor: no automated scorer is the official examiner. Use it to find and fix patterns, not to predict your exact final band to a decimal place.
The review routine that works
Write the essay under 40 minutes, timed, no dictionary. Submit it. Read the band for each criterion before you read a word of the commentary, and note the lowest one.
Open the official band descriptor for that criterion at your band and at the band above. Read both. The difference between them, in plain English, is your entire instruction.
Now rewrite only the part that fixes that gap. Not the whole essay. If Task Response was lowest because body paragraph two had no example, rewrite body paragraph two. Then write a new essay on a different prompt attacking the same weakness, and check whether that criterion moved.
Repeat until that criterion is no longer your lowest. Then start again with whatever is.
The mistake to avoid
Submitting twenty essays and reading twenty sets of feedback is not practice, it is a hobby. The band moves when you fix one pattern at a time and verify it moved. One essay a day with a focused rewrite beats three essays a day skimmed.
The other mistake is submitting your best work. Feedback on the essay you already knew was good tells you nothing. Submit the ones you rushed, the prompts you found awkward, the types you avoid. That is where the marks are.
Get your essays scored against all four criteria
On IELTSVega you can write real Academic and General Training Task 1 and Task 2 prompts in a typed editor with a live word count and no spell-checker, exactly as the exam works, and get instant AI band scores broken down by Task Response, Coherence and Cohesion, Lexical Resource and Grammatical Range and Accuracy, with specific feedback on what is capping each one.