WordieVocabulary Size Estimator
Tick the words whose meaning you know. The checklist samples eight frequency bands and includes fake words to correct for guessing, then estimates how many English word families you know.
Tick every word whose meaning you know. Be honest: some of these words are not real.
This vocabulary size estimator is a quick yes/no checklist. You tick the English words you know, and it estimates how many word families you know by sampling eight frequency bands from the 1,000 most common words up to the 20,000 level. Ten invented words catch over-confident ticking. Expect a rough estimate, useful for choosing reading material and setting goals, not a certified score.
How the estimate is calculated
Words are sampled from frequency bands, groups of word families ranked by how often they appear in large English corpora. Each band in the test stands for a range of the frequency list:
| Band | Word families covered | Band size |
|---|---|---|
| 1k, 2k, 3k | 1–3,000 | 1,000 each |
| 5k | 3,001–5,000 | 2,000 |
| 8k | 5,001–8,000 | 3,000 |
| 10k | 8,001–10,000 | 2,000 |
| 14k | 10,001–14,000 | 4,000 |
| 20k | 14,001–20,000 | 6,000 |
For each band, the share of sample words you ticked (the hit rate, h) is multiplied by the band size, and the bands are added up. If you tick fake words, the tool applies the standard correction for guessing: with a false-alarm rate f (fake words ticked ÷ 10), each band's hit rate becomes (h − f) ÷ (1 − f), floored at zero. Ticking 2 of 10 fake words turns a 60% hit rate into 50%.
Why the test uses fake words
Yes/no tests are fast because you do not have to prove you know each word, but that makes them easy to inflate. Meara and Buxton (1987) proposed mixing in plausible non-words: anyone who claims to know fennacious is probably also ticking some real words they only half-recognize. The same design is used in LexTALE (Lemhöfer & Broersma, 2012), a short yes/no test used in research to measure English proficiency. Tick a word only if you could give its meaning, not just because it looks familiar.
How to interpret your result
- Under 3,000: focus on high-frequency words; they give the biggest gain in comprehension per word learned.
- 3,000 to 8,000: add the Academic Word List if you study or work in English, and read widely at a comfortable level.
- 8,000 to 9,000+: Nation (2006) estimated this is what you need for about 98% lexical coverage of novels and newspapers. See how many words you need to be fluent.
The result measures receptive vocabulary, words you recognize when reading. Your productive vocabulary, the words you can use in speech and writing, is usually much smaller.
Limitations
Seven words per band is a small sample, so one word more or less moves a band's estimate by about 14%. The band assignments are approximate, based on general English frequency rather than one specific published list, and rare-band words may be common in your field. Self-report also differs from demonstrated knowledge. For a validated measure, use a full Vocabulary Size Test, which uses multiple-choice items across 14 or 20 bands. Retaking this checklist gives the same words in a new order, so it works for a quick check, not for tracking progress month to month.
Sources: Meara, P. & Buxton, B. (1987). An alternative to multiple choice vocabulary tests. Language Testing, 4(2). Lemhöfer, K. & Broersma, M. (2012). Introducing LexTALE. Behavior Research Methods, 44. Nation, I. S. P. (2006). How large a vocabulary is needed for reading and listening? Canadian Modern Language Review, 63(1). Brysbaert, M. et al. (2016). How many words do we know? Frontiers in Psychology, 7.
How to use this tool
- Read each word and tick it only if you could explain its meaning or use it in a sentence.
- Leave words unticked if you have only seen them or are guessing. Some items are invented words.
- Watch the estimate update as you tick, then click Show results for a band-by-band breakdown.
- Click Reveal fake words to see which items were not real English words.
Frequently asked questions
How accurate is this vocabulary size estimate?
It is a rough estimate. With seven words per band, one word more or less changes a band's result noticeably, so treat the number as a range of a few thousand word families rather than an exact score.
Why are there fake words in the test?
Invented words detect over-confident ticking. If you tick words that do not exist, the tool assumes you also ticked some real words you do not really know and lowers the estimate accordingly.
How many English words does a native speaker know?
Estimates vary with the counting method. Brysbaert et al. (2016) estimated that a 20-year-old native speaker of American English knows about 42,000 lemmas, derived from roughly 11,000 word families. Older studies of university graduates gave higher figures of around 17,000 to 20,000 word families.
How many words do I need to read English comfortably?
Research by Paul Nation (2006) suggests about 8,000 to 9,000 word families for comfortable reading of authentic texts such as novels and newspapers, and 6,000 to 7,000 for spoken English.
Is this the same as the Vocabulary Size Test?
No. Nation and Beglar's Vocabulary Size Test uses multiple-choice items. This tool uses a quicker yes/no checklist in the style of Meara and Buxton (1987), which is faster but less precise.
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