Is grammar important in IELTS Speaking?

The criterion has two halves, and they pull against each other

Grammatical Range and Accuracy is one measurement of two things. Range is about the grammatical resources available to you, which is what decides how complicated an idea you can express at all. Accuracy is about using those forms correctly and appropriately.

IELTS publishes what examiners attend to on each side. For range: how long your spoken sentences are, whether you use subordinate clauses inside clauses and phrases, how complex your verb phrases get — auxiliaries in continuous and perfect aspect, modality, the passive — and whether you can rearrange a sentence to put the emphasis where you want it.

For accuracy, two indicators only: error density, meaning how many grammatical errors appear in a given amount of speech, and the communicative effect of those errors — what they do to intelligibility and to the precision of what you meant. That second one is the indicator candidates underestimate. An error that leaves your meaning intact is not weighed the same as one that makes the listener guess.

How many mistakes each band allows

The public descriptors are unusually forgiving here, and reading them in order is reassuring:

No band asks you to be perfect. What changes from band to band is how often a whole sentence comes out clean, and whether the mistakes that remain are a pattern or a one-off.

Which of your mistakes is actually holding you down

Split your errors into two piles.

Systematic errors repeat everywhere: the missing third-person “s”, the dropped article, the preposition you always get wrong, the past tense you avoid by telling stories in the present. These raise error density across the whole test and are exactly what the upper bands stop tolerating. They are also the quickest to fix, because there are usually only three or four of them.

One-off errors are the slips that happen once, under pressure, in a structure you normally handle. The Band 8 description treats mistakes of that kind — unsystematic, not part of a pattern — as something it can live with. Spending practice time on those is spending it in the wrong place.

What to do about it

Record a full answer, transcribe two minutes of it, and mark every error. If the same mistake appears four times, you have found your work. If twelve different mistakes each appear once, your problem is range, not accuracy.

Then widen deliberately. Pick one structure — a relative clause, a conditional, a perfect tense — and use it in ten answers on ten different topics until it stops being a decision. The common grammar mistakes post lists the repeat offenders worth checking first, and the descriptor explorer shows what the next band up expects on this criterion alone.