The unit of measurement is the sentence
Band 7 asks for frequent error-free sentences. That phrasing matters more than it looks: the thing being counted is the sentence, not the error.
So a sixty-word sentence with one broken clause in the middle is a failed sentence. Three twenty-word sentences, each correct, are three successful ones. Same amount of writing, completely different result.
But you still need range
The criterion is Grammatical Range and Accuracy. Writing nothing but short simple sentences protects your accuracy and caps your range — the same trap as in speaking, arrived at from the other direction.
What you want is controlled complexity: complex sentences you can finish.
| Structure | Example |
|---|---|
| Although / while (concession) | Although the policy is expensive, it addresses the root cause. |
| Which / who (relative clause) | Cars, which carry few people, occupy most of the road space. |
| If / unless (conditional) | If fares were subsidised, ridership would rise. |
| -ing opener (participle) | Having removed tuition fees, Scotland saw applications rise. |
| Passive | Fees were abolished in 2008. |
| Not only … but also | Not only is it cheaper, but it is also faster. |
Each of these is one clause added to another. None of them requires a sixty-word sentence. Complexity is about structure, not length — and this is the distinction that gets people out of a 6.
Punctuation is in this criterion, and it is where the marks go
Punctuation is explicitly part of Grammatical Range and Accuracy, and it is the part candidates ignore. One error dominates all others in IELTS essays.
The third fix is the best one, because it adds a complex structure at the same time — you repair the accuracy problem and gain range in a single move.
Which errors cost the most
| Costly — meaning breaks | Cheap — the reader recovers |
|---|---|
| Comma splices and run-on sentences | One missing article |
| Wrong tense in a sequence of events | A slightly odd preposition |
| Subject–verb disagreement (the data shows / show) | An occasional awkward phrase |
| A relative clause with no clear antecedent | A repeated linker |
| Dropped -s / -ed (deletes number and time) |
Fix the left column first. The right column is worth very little and is not where anyone's band is being lost.
What each band looks like
| Band | What it looks like |
|---|---|
| 5 | Limited range. Attempts at complex sentences are less accurate than simple ones. Punctuation is faulty. |
| 6 | A mix of simple and complex forms. Errors occur but rarely reduce communication. |
| 7 | A variety of complex structures. Frequent error-free sentences. Good control of grammar and punctuation, with few errors. |
| 8 | Wide range. Majority error-free. Occasional slips only. |
| 9 | Full range, natural, accurate. |
Band 5 contains a sentence worth reading twice: attempts at complex sentences are less accurate than the simple ones. That is precisely the failure this page is about — reaching for complexity you cannot control.
What moves you up a band
| If you are at… | The change that moves you |
|---|---|
| 5 → 6 | Kill the comma splices. Every sentence must be a complete sentence. |
| 6 → 7 | Add controlled complexity — although, which, a conditional, a passive — in sentences short enough to finish cleanly. |
| 7 → 8 | Vary how you build complexity, and clean up the residue: articles, agreement, prepositions. |
How to practise
- Count your clauses. Take an essay you wrote and mark every sentence with more than one clause. Fewer than half? That is your band 6.
- Then check the long ones. Any sentence over about 30 words — read it aloud. If you run out of breath or lose the thread, so did the examiner.
- Split, then join properly. Break your longest sentence into two, then rejoin them with because, although, or which. That is the whole skill.
- Hunt comma splices specifically. Look at every comma and ask whether both sides could stand alone as sentences. If yes, it is an error.
Aflo marks Grammatical Range and Accuracy separately, shows each error in place, and gives you an improved version of your own writing — so you can see what the sentence should have been, rather than guessing.
Frequently asked questions
Are long sentences good for IELTS Writing?
No. Band 7 asks for frequent error-free sentences, so the sentence is the unit being counted. One long sentence with a broken clause in it is a failed sentence; three short correct ones are three successes. Complexity comes from structure, not length — when a sentence starts getting away from you, end it.
What is a comma splice and why does it matter?
Joining two complete sentences with a comma: 'Pollution is a serious problem, it affects everyone.' It is the single most common grammar error in IELTS essays, and punctuation is explicitly marked inside this criterion. Fix it with a full stop, a semicolon, or best of all a joining word like because — which repairs the error and adds a complex structure at the same time.
Should I write simple sentences to stay accurate?
That protects accuracy and caps your range, and the criterion is both. What you want is controlled complexity: complex sentences short enough that you can finish them cleanly. Although, which, if, and the passive all add a clause without adding length.
Which grammar errors cost the most in IELTS Writing?
The ones that break meaning: comma splices and run-ons, wrong tense in a sequence, subject-verb disagreement, and dropped -s or -ed endings, which delete number and time. Missing articles and odd prepositions are cheap by comparison.