Find Out How Many Words You Know
Free adaptive test · measures up to 42,000 words · A1–C2 CEFR placement · 8 minutes · no sign-up
Take the free vocabulary size test →Contents
- The short answer: how many words do adults know?
- What counts as "knowing" a word?
- Vocabulary size by age
- How education and reading affect your score
- What is a good vocabulary score?
- Vocabulary size for English learners (CEFR)
- How vocabulary size is measured
- Can you increase your vocabulary as an adult?
- Frequently asked questions
The Short Answer: How Many Words Do Adults Know?
The most reliable large-scale data comes from Brysbaert, Stevens, Mandera & Keuleers (2016), who surveyed over 220,000 people using a web-based vocabulary test. Their key finding: the average American adult knows approximately 27,000 word families, with most adults falling in the 20,000–35,000 range.
These numbers refer to receptive vocabulary — words you can recognise and understand when you encounter them. Your productive vocabulary (words you actively use in speech and writing) is typically 30–50% smaller.
The surprising finding: In the Brysbaert study, 20-year-olds and 60-year-olds had almost the same average scores. Vocabulary does not peak at 30 and decline — it keeps growing throughout adult life as long as you keep reading.
What Counts as "Knowing" a Word?
Vocabulary researchers use word families as their basic unit — a word family includes the base word and all its regular inflected and derived forms. So run, runs, ran, running, runner all count as one word family. This makes comparisons more consistent across studies.
"Knowing" a word, in research terms, means being able to recognise it and understand its core meaning when you encounter it in context. It does not require knowing every nuance, collocation, or derivation — just reliable recognition. This is sometimes called receptive or passive knowledge.
This is why vocabulary tests present you with a word and ask whether you know it — not whether you could produce it spontaneously. The vocabulary size test on this site uses the same recognition-based approach, calibrated against the Brysbaert corpus.
Vocabulary Size by Age
Vocabulary grows rapidly in childhood, slows in adulthood, but — crucially — never stops. Here are the typical benchmarks across the lifespan:
| Age | Typical vocabulary size | Notes |
|---|---|---|
| 4 years | ~4,000–6,000 words | Rapid acquisition phase begins |
| 8 years | ~8,000–10,000 words | Reading reinforces spoken vocabulary |
| 12 years | ~12,000–15,000 words | Acquisition ~2,000–3,000 words/year |
| 18 years | ~18,000–22,000 words | Rate slows as high-frequency words saturate |
| 25 years | ~20,000–28,000 words | Adult plateau begins; reading drives growth |
| 40 years | ~23,000–32,000 words | Steady growth for regular readers |
| 60+ years | ~25,000–35,000+ words | Vocabulary often peaks here |
Sources: Brysbaert et al. (2016), Nation (2001), Zechmeister et al. (1993).
Want to see how your score compares to your age group? The free vocabulary size test gives you a precise word count in about 8 minutes.
How Education and Reading Affect Your Score
The Brysbaert study found that reading habits are a stronger predictor of adult vocabulary than formal education. Two people with the same level of schooling can differ by 15,000 words or more depending on how much they read.
| Group | Typical vocabulary size |
|---|---|
| Avid reader (reads daily) | 30,000–42,000+ |
| College-educated adult | 28,000–35,000 |
| Average adult (native speaker) | 20,000–28,000 |
| Occasional reader | 15,000–22,000 |
| Rarely reads for pleasure | 10,000–18,000 |
The mechanism is simple: most vocabulary is acquired incidentally through reading, not through deliberate study. Each new word encountered in context has a roughly 1-in-10 chance of being retained after a single exposure, and a much higher chance after several exposures across different texts. Avid readers encounter a wider variety of vocabulary, more often, across more contexts — which is why they accumulate vocabulary at a faster rate throughout adult life.
What Is a Good Vocabulary Score?
There is no single "good" score — it depends on your background and goals. Here are the benchmarks that matter most:
| Score (word families) | What it means |
|---|---|
| 35,000+ | Excellent — top quartile for educated native speakers; avid reader |
| 28,000–35,000 | Strong — above average for native speakers; college-educated range |
| 20,000–28,000 | Average for adult native speakers |
| 15,000–20,000 | Below average for native speakers, but functional |
| 9,000–12,000 | C2 level for English learners — near-native proficiency |
| 6,000–9,000 | C1 level — advanced English learner; professional fluency |
| 3,500–6,000 | B2 level — conversational fluency threshold |
| 2,000–3,500 | B1 level — intermediate; can manage everyday situations |
| 1,000–2,000 | A2 level — basic communication |
| 500–1,000 | A1 level — beginner |
Vocabulary Size for English Learners (CEFR)
If English is not your first language, your vocabulary score maps onto the CEFR scale — the international standard for language proficiency used in exams like IELTS, TOEFL, and Cambridge. The key milestone is B2 (around 5,000 words) — the point at which English stops feeling like constant work and comprehension becomes genuinely comfortable.
| CEFR Level | Vocabulary size | What you can do |
|---|---|---|
| A1 | 500–1,000 words | Introduce yourself, handle very simple exchanges |
| A2 | 1,000–2,000 words | Manage routine transactions, understand simple texts |
| B1 | 2,000–3,500 words | Travel independently, follow news, write basic reports |
| B2 | 3,500–6,000 words | Fluent conversation, understand most authentic content |
| C1 | 6,000–9,000 words | Academic and professional fluency, implicit meaning |
| C2 | 9,000–12,000 words | Near-native proficiency, full nuance and precision |
How Vocabulary Size Is Measured
Vocabulary size tests work by sampling from the full frequency range of English — from the most common words (which everyone knows) to rare words (which only avid readers encounter). By testing a representative sample across frequency bands, the algorithm estimates how many words you know in total.
The most accurate tests use an adaptive algorithm that adjusts difficulty in real time based on your answers. If you answer correctly, the next word is less common; if you make a mistake, it drops back to more frequent words. After 20–30 questions, the algorithm has enough data to estimate your total vocabulary with a margin of error of approximately ±3%.
Our free vocabulary size test is calibrated against the Brysbaert & Keuleers (2016) corpus — the largest English vocabulary dataset ever assembled, based on 222,000 participants. This is the same dataset used in the research benchmarks on this page, so your score is directly comparable to the published averages.
How the test works: You are shown one word at a time and asked whether you know it. You do not have to define it — just indicate whether it is familiar. The algorithm tracks your yes/no pattern across frequency bands and calculates your estimated vocabulary size at the end.
Can You Increase Your Vocabulary as an Adult?
Yes — and this is one of the more encouraging findings in language research. Unlike many cognitive abilities, vocabulary does not peak in early adulthood and then decline. The Brysbaert study found that adults in their 60s and 70s had larger vocabularies on average than adults in their 20s.
The most effective strategies, ranked by impact:
- Read widely. This is the single most powerful factor. Reading exposes you to a wider variety of vocabulary, in more contexts, than any other activity. Fiction and non-fiction outside your professional domain are especially valuable because they contain vocabulary you would not encounter in your daily work.
- Read at the edge of your comfort zone. Texts where you know 90–95% of words are the optimal input zone — unfamiliar words appear often enough to be noticed, but not so often that comprehension breaks down. Staying in comfortable territory limits acquisition.
- Pay attention to unfamiliar words. Incidental acquisition is passive; it only works at moderate rates. Stopping to look up an unknown word when it appears three times in a week can be more effective than hoping it will eventually stick on its own.
- Use spaced repetition for targeted vocabulary. For learners with specific goals (an exam, a professional domain, a CEFR level), systematic flashcard-based study using spaced repetition (Anki, Quizlet) can accelerate acquisition in targeted areas. This supplements reading but does not replace it.
After taking the vocabulary size test, you will see your score broken down by frequency band — which can help you identify which part of the vocabulary range to focus on next.
Find Out Your Exact Score
Our free adaptive test measures your vocabulary against the benchmarks on this page. Native speaker track (up to 42,000 words) or CEFR learner track (A1–C2). Takes 8 minutes, no sign-up required.
Take the free vocabulary size test →Frequently Asked Questions
How many words does the average person know?
The average native English-speaking adult knows approximately 27,000 word families, according to the Brysbaert et al. (2016) study of over 220,000 participants. Most adults fall between 20,000 and 35,000, with the range depending heavily on reading habits rather than age or education level.
How can I find out how many words I know?
Take a calibrated vocabulary size test. Our free test uses an adaptive algorithm and gives an accurate estimate in about 8 minutes. It measures up to 42,000 words for native speakers, or places English learners on the A1–C2 CEFR scale. No sign-up required.
How many words do I need to know to be fluent in English?
Research on vocabulary coverage suggests that around 8,000–10,000 word families is enough for comfortable reading and listening in most everyday and professional contexts. At 5,000 words (B2 level), you understand approximately 90% of written text — enough for functional fluency. Full academic fluency typically requires 9,000–12,000 words.
What is a good vocabulary size for a native English speaker?
For adult native speakers: 20,000–28,000 is average; 28,000–35,000 is strong; above 35,000 is excellent. Avid readers regularly score 40,000+. The wide range within any age group reflects reading habits more than any other factor.
What is a good vocabulary size for an English learner?
The key milestone is B2, at around 3,500–6,000 words — the threshold at which English stops feeling like constant effort and conversation with native speakers becomes genuinely natural. C1 (6,000–9,000 words) is required for academic and professional fluency. C2 (9,000–12,000 words) represents near-native proficiency. See the full CEFR vocabulary guide for detailed breakdowns.
Does vocabulary size decline with age?
No — vocabulary is one of the few cognitive abilities that reliably grows throughout adulthood. The Brysbaert study found no evidence of decline before very old age. People in their 60s scored higher on average than people in their 20s. Reading consistently is the most reliable way to keep adding to your vocabulary throughout life.
Related Reading
- Average Vocabulary Size by Age — detailed research data on vocabulary benchmarks across the lifespan
- Vocabulary by Age — milestones from age 1 to 18+, with red flags and growth rates
- Native Speaker Vocabulary — how native and advanced-learner ranges compare
- Most Common English Words — the top 100, 1,000 and 5,000 by frequency
- CEFR Vocabulary Levels Guide — how learner vocabulary maps to A1–C2, with word count benchmarks for each level
- English Vocabulary Test — the free adaptive test that measures your vocabulary size
- Methodology & Science — how our scores are calibrated against the Brysbaert corpus