English vocabulary tests: why your number changes, and what to do with it
Your vocabulary size is the best single predictor of how well you read in English. Comfortable reading starts when you know about 98% of the words on a page (Hu and Nation, 2000), and for most written English that takes around 8,000 to 9,000 word families (Nation, 2006). A vocabulary test tells you how far you are from that point.
The trouble starts when you take more than one. Learners who test themselves on several free sites find the numbers disagree, sometimes by a factor of two. This page collects what they found, explains why it happens, and shows how to use a result anyway.
One learner, five tests, almost double
One learner shared the results of five free tests:
| Test | Result |
|---|---|
| A Preply-style test | 11,913 words |
| my.vocabularysize.com | at least 7,400 word families |
| arealme | 6,729, "like a 10-year-old American" |
| lingedia | about 9,900 words, C1, "like a 15-year-old native speaker" |
| Oxford Online English | 31 out of 40, B1 Intermediate, in 3 minutes 59 seconds |
That is anything from 6,700 to 11,900, and from B1 to C1. Their own conclusion: every site gives a different number, so take it as a rough idea.
Another learner tried four tests and estimated their real vocabulary at about 15,000: testyourvocab gave 14,400, the Chinese apps Baicizhan 16,905 for reading and 17,070 for listening, MaiMemo 17,762, and Daily English Listening 15,691 with a stated range of 14,750 to 15,691 after 53 questions. Their advice was to take the average.
It is not always this messy. A third learner found testyourvocab (5,786 words) and my.vocabularysize.com (at least 5,800 word families) almost identical. A fourth got four results that all landed near 9,000: Preply 9,620, Eudic 9,736, Shanbay 9,972 for reading and Baicizhan 8,057 for reading.
Why the numbers disagree
Words are not word families. A word family counts decide, decided, decision and decisive once; a word count may count them four times. Under the five-test post above, a commenter multiplied the 7,400 word families by 1.5 and got about 11,100 words, close to the 11,913 from the other site. One learner who studied English at university tested on three sites and got at least 9,700 word families on VocabularySize.com (all 140 questions), 10,500 word families and C1 on BRAVE, and about 29,000 words on Test Your Vocab. They had stopped Test Your Vocab after 52 words, when its range was still 14,000 to 140,000, so they didn't treat it as a baseline. Different question types, lengths and units mean the three numbers cannot be compared directly.
Tick-box tests depend on your honesty. On tests where you tick the words you know, ticking loosely pushes the number up and being over-cautious pushes it down. A commenter's rule: if you only vaguely recognise a word, look it up before you decide whether to tick it.
Multiple choice lets you recognise what you can't recall. One learner who had studied about 3,000 core words scored 4,588 on a listening test and said their real vocabulary should be cut in half: with options in front of them they recognised words they could not remember without. Another scored over 6,000 the first time by guessing, and 5,200 when they honestly chose "don't know". One learner watched an app's estimate go from about 7,500 after a hundred-odd questions to 8,500 after two hundred and 13,000 a week later, while they were still studying for China's CET-6 exam.
Retesting changes the result. One learner noted that Eudic's 120-question test gave a range of 8,470 to 9,736, that the score dropped when they retested an hour later with new questions, and that it seemed to get more accurate the more questions they answered.
Most tests check one meaning. A test counts you as knowing table or novel if you know the common meaning. It won't notice that you miss table the proposal (postpone it) or a novel idea (a new one). This is the most common criticism of vocabulary tests, and a fair one.
Which test to use for what
The learner with the three-site comparison ended up with a simple rule:
- Quick check or regular monitoring: BRAVE, which takes about two minutes.
- A stable baseline you can compare against later: VocabularySize.com, 140 questions.
- Just curious: Test Your Vocab, which swings widely.
Whatever you choose, compare yourself only with yourself on the same test. A jump from one site's number to another's tells you nothing.
Your number and your real English
A score can go down while your English goes up. One learner tested at 4,700 and remembered scoring about 5,700 in the last year of high school, so their first thought was that they had gone backwards. But since the previous summer they had been watching English-only YouTube channels, American TV series and live AI product launches without trouble, which they could not do in high school.
The reverse also happens. One learner who tested their vocabulary every month had been stuck between 16,000 and 17,000 for months, after going through word books for China's TEM-8 English exam seven or eight times, IELTS three times and about half of GRE. They read at least one Economist article a day and copied down every unknown word. Their account of what that level means: politics and economics articles have fewer than five unknown words each, history and biographies are easy, Flipped is readable but classic novels are still hard; they watch Friends basically without subtitles, follow 60 to 70% of Yes, Minister and miss most of The Big Bang Theory. In their words, between 10,000 and 20,000 words there is a chasm.
What to do with your result
Use your number to decide what to read next, not to grade yourself. The thresholds learners and researchers mention most:
- Under about 3,500: many learners say the first few thousand common words are worth learning directly, then reading takes over.
- About 4,000 to 5,000: easy graded readers. One adult who had scraped through China's CET-4 and CET-6 exams with test tricks estimated they had learned 4,000 to 5,000 words but could actually use 2,000 to 3,000. After less than a month of reading Oxford Bookworms levels one to four with the audio, they estimated their usable vocabulary had risen to 4,000 to 5,000, and level five had almost no unknown words.
- About 8,000: the point where a novel like Harry Potter stops being a dictionary marathon. The most-liked comment under one learner's post about being stuck in its first chapter put the minimum at 8,000.
- 8,000 to 9,000 word families: most written English at 98% coverage (Nation, 2006).
- 10,000 and up: progress comes from reading and watching widely, because the remaining words are rare.
Our guide to extensive reading explains how to choose books at your level.
Where Solaread helps
Solaread uses a vocabulary test for a practical job rather than a score. It takes about two minutes: twenty words, one at a time, Know it or Don't know. From the result it predicts which words in your book you probably don't know and puts a short translation right after each of them, in the same line. The more you read, the less it marks: it remembers the words you saved and the words you marked as known, so the help follows your level.
Questions
Which free English vocabulary test is the most accurate?
None of them agree exactly; use one longer test such as VocabularySize.com as a baseline and retest on the same one.
Why do vocabulary tests give such different results?
They count different units (words or word families), use different question types and lengths, and tick-box tests depend on how honestly you answer.
How many words do I need to read a novel in English?
About 8,000 to 9,000 word families for most novels; learners often name 8,000 as the minimum for Harry Potter.
How many English words does a native speaker know?
Estimates for educated adult native speakers are commonly around 20,000 word families.