The IELTS Speaking Test is marked or graded using score from 1 to 9 on four criteria, as follows:
Fluency and Coherence: This means how fluently a candidate speaks or in other words, how well one maintains a flow of speech while developing the answer on the given topic or question. In addition, the examiner determines the cohesive features or connectives are appropriately used.
Lexical Resource/ Vocabulary: This means a candidate has to use a wide range of vocabulary precisely. An examiner usually checks whether you are able to use less common and idiomatic expressions skilfully.
Grammatical Range and Accuracy: This means a candidate has to use a wide range of structures appropriately. An examiner will not only look for the tenses, but also check whether you organize your sentences well.
Pronunciation: This means a candidate uses a full range of pronunciation features accurately such as intonation, stress, pauses, etc.