Average vocabulary size by age: what the research measures

There is no single vocabulary-size chart that works from toddlerhood to old age. The number changes with the test, the language and what counts as one word. Before comparing your score with an age average, check those details.

For your own starting point, try our free English vocabulary test. It estimates word recognition; it does not measure everything you can do in English.

Adult vocabulary size by age

In a 2016 study, Brysbaert and colleagues estimated the following receptive vocabularies for native English speakers:

Age	Lemmas recognised	Base words / word families
20	about 42,000	about 11,100
60	about 48,200	about 13,400

These are the study’s median estimates, not targets everyone should reach. Its family-grouping rules matter: a different test can group the same vocabulary differently and produce a different total. Recognition here can be as shallow as knowing that a word exists.

The older group had a larger estimated vocabulary, but this was a comparison between age groups. It does not tell you how many words one particular person will learn over the next 40 years.

Source: Brysbaert et al., How Many Words Do We Know? (2016), Table 4.

Why children’s vocabulary counts need a separate chart

Wordbank collects researchers’ data from the MacArthur-Bates Communicative Development Inventories. These parent-report instruments record early language development. Its vocabulary-norms explorer lets you compare growth curves for different languages and demographic groups.

A number from a parent checklist is not interchangeable with an adult’s dictionary-based test estimate. Check whether the measure concerns words a child understands or says, which language and instrument were used, and whether the number is a mean, a median or a percentile.

That is why we do not join a toddler checklist score and an adult word-family estimate into one smooth growth curve. It would make unlike measurements look comparable. For children’s data, use the relevant Wordbank instrument and age range rather than this site’s adult vocabulary test.

What counts as a word?

Imagine a test that includes walk, walked, walking and walker. You might recognise all four forms. One scoring method could count four items; another could group the inflected forms under walk; a broader family could also include walker.

The everyday question, “How many words do I know?”, hides that choice. Look for a test that names its counting unit before comparing its result with another website or a published study.

Recognition and use also ask different questions. Recognising reluctant in a sentence does not necessarily mean you would choose it while speaking. Neither result is a complete description of your language ability.

Can you compare an English learner with a native speaker of the same age?

Age alone is a poor match for that comparison. A learner may use English at work every day, study it only in class, or read it often without speaking it. Choose material that fits what you want to do in English, then look for gaps in that material.

The Council of Europe’s CEFR levels describe abilities through can-do statements. A vocabulary estimate can help you choose practice material, but it cannot certify a CEFR level or replace an assessment of reading, listening, speaking and writing.

Our A1 to C2 English word lists include definitions and example sentences. Start with a list where you know most entries, and practise the words you cannot yet use in a sentence of your own.

How to track your own vocabulary

Keep the test and its counting method consistent. If you switch from a word-family test to a lemma test, a higher number may reflect the change of measurement rather than new knowledge.

Do not rehearse a test’s exact words before repeating it. Note the date and score, then spend time reading, listening and using unfamiliar words before checking again. Treat small score changes cautiously: a short sample can vary between attempts.

Our English vocabulary test is a quick browser estimate with no sign-up. For repeat attempts and saved results, see the Android vocabulary app.