Why vocabulary range matters in IELTS
Lexical Resource is one of the four criteria in both IELTS Writing and Speaking, so it accounts for a quarter of each score. The band descriptors reward a “wide range of vocabulary” used “fluently and flexibly”, including less common items, with awareness of style and collocation. In practice, essays at band 7 and above use noticeably more topic-specific and academic words than essays at band 5 or 6.
How the estimate is made
The checker compares every word with two openly licensed lists created by Browne, Culligan and Phillips: the New General Service List (NGSL), which covers around 92% of the words in typical English texts, and the New Academic Word List (NAWL). Words are grouped by frequency — the most common 500 families as A1, then A2, B1 and B2 — while academic words and words outside both lists show your more advanced range. The overall level is estimated from the proportion of your words that go beyond the most frequent 1,800 families.
Worked example
Compare “Many people think the government should spend more money on buses” with “A significant proportion of citizens argue that public funding should be allocated to transport infrastructure, thereby reducing congestion.” The first sentence uses only very frequent words and comes out at A2. The second adds the academic words allocate and thereby and less frequent words such as infrastructure and congestion, which pushes the profile towards C1 — as long as the words are used naturally.
Improving your profile
- Learn words in topic groups (environment, technology, education) with their common collocations.
- Replace a few very general words (good, big, thing) with precise ones — but never use a word you are unsure of.
- Keep an eye on repetition: if lexical diversity is low, paraphrase key nouns and verbs.
- Check the flow with the linking words checker as well.
Word list credits
New General Service List 1.2 and New Academic Word List 1.2 by Browne, C., Culligan, B. and Phillips, J., used under the Creative Commons Attribution-ShareAlike 4.0 licence. The CEFR banding is our own approximation.