A team at Ghent University once put a simple test online. It showed a list of 100 letter strings, some real English words and some invented ones, and asked a single question: which of these do you know? 221,268 people took it. From their answers, the researchers estimated, in a 2016 paper, that an average 20-year-old native speaker of American English knows about 42,000 words.
You don't need anything close to that to be fluent. To understand almost every word in what you read, research points to about 8,000 to 9,000 word families. For speech, the estimate is about 6,000 to 7,000. Reading with some effort is possible from about 4,000 to 5,000. These numbers are useful guides, but a recent replication suggests they are less exact than textbooks make them sound.
What counts as a word
Every answer to "how many words" depends on what you count. Two units matter here.
A lemma is a word in its dictionary form, with its grammatical forms counted together. Speak, speaks, spoke and spoken are one lemma.
A word family goes further and adds related words built from the same base. Teach, teacher and teaching belong to one family. Once you know one member, the others are much easier to understand, which is why learning research usually counts families.
How many words native speakers know
The Ghent study by Brysbaert and colleagues, published in Frontiers in Psychology, tested people on a list of 61,800 lemmas. Each person saw 67 real words and 33 invented ones. People were warned about the invented words, and every "yes" to one of them was subtracted from their score, which corrected for guessing.
The estimate for an average 20-year-old was 42,000 lemmas, which come from about 11,100 word families. The lowest 5 percent knew about 27,000 lemmas and the highest 5 percent about 52,000. Learning doesn't stop at 20: between 20 and 60, the average person adds about 6,000 lemmas, roughly one new word every two days.
There is an important detail in that paper. "Knowing" a word in this test can mean no more than recognising that it exists. Native vocabularies are huge, but part of that knowledge is shallow.
How many words a learner needs
For learners, the more useful question is coverage: what share of the words in a text do you need to know to understand it? The idea comes from a 2000 study by Hu and Nation, which tested how well readers understood texts with different numbers of unknown words. It led to a widely used rule: to read comfortably without a dictionary, you need to know about 98 percent of the words, or 49 out of every 50.
In 2006, Paul Nation used large lists from the British National Corpus to translate that rule into vocabulary sizes. In the Canadian Modern Language Review, he estimated that 98 percent coverage takes 8,000 to 9,000 word families for written English and 6,000 to 7,000 for spoken English. Speech needs fewer, probably because everyday talk leans more on common words.
In 2010, Batia Laufer and Geke Ravenhorst-Kalovski added a second, lower threshold in Reading in a Foreign Language. About 4,000 to 5,000 word families give around 95 percent coverage, one unknown word in 20, which they called a minimal level for reading. They also found that even small gains in vocabulary improved comprehension, although they barely changed coverage.
A threshold, or a slope?
The 98 percent figure became one of the best-known numbers in language teaching. But it rests on a small study: Hu and Nation's result came from 66 university students in New Zealand. In 2023, Benjamin Kremmel and colleagues repeated the study with 104 adult learners in Sri Lanka and published it in Language Learning. The results of the original study "could not be fully replicated".
So treat these numbers as signposts, not as walls. Understanding grows with every word you add. There is no single number at which a language suddenly opens.
One more limit: almost all of this research is about English. In languages with many endings, such as Polish or Finnish, one word family produces many more forms, so the counts may not transfer one to one.
What this means for you
- Learn the frequent words first. They come up again and again, so each one pays off quickly. The rare ones can wait until you meet them.
- Learn families, not single forms. When you learn a word, notice its relatives. Knowing one makes the others cheap.
- Use the one-in-twenty test. Count the unknown words on a page. If more than about one in 20 is new, the text is hard work; near one in 50, you can read for pleasure.
- Don't wait for a number to start reading and listening. Comprehension improves word by word, and reading itself adds words.
- Know words well enough to use them. Recognising a word is the first step. Being able to produce it in a sentence is what makes you fluent.
Qlango is built around that last point. Every new word comes with example sentences, so you meet it in context rather than on a list. Spaced repetition brings each lesson back after one, two, four and eight days and then once more. Many exercises ask you to write the answer yourself, which trains producing a word, not just recognising it. To see how vocabulary grows with each level, read our guide to the CEFR levels, and compare the methods in how to learn vocabulary faster.
The 221,268 people in Ghent knew tens of thousands of words, many of them barely. A learner who truly knows the right few thousand can talk, read and argue in a new language. Count families, start with the frequent ones, and here is how long it takes to learn a language to get there.
Frequently asked questions
How many words do you need to be fluent in a language?
Research on English suggests about 8,000 to 9,000 word families to understand almost every word in written texts, and about 6,000 to 7,000 for spoken language. With 4,000 to 5,000 word families you can read with some effort. Fluency also depends on how well you can use the words, not only on how many you recognise.
How many words does the average person know?
A 2016 study at Ghent University estimated that an average 20-year-old native speaker of American English knows about 42,000 lemmas, from about 11,100 word families. Between 20 and 60, people add roughly one new word every two days.
How many words do you need to have a conversation?
Research on speaking is thinner than on reading. For understanding speech, Nation estimated 6,000 to 7,000 word families to know 98 percent of the words. Simple conversations need fewer, because everyday talk relies heavily on the most common words.
How many words are in the English language?
It depends on what you count as a word. The Ghent researchers built a list of 61,800 lemmas for their test, while the 2014 Collins Scrabble Words list has 267,751 entries, including many rare and inflected forms. No one knows all of them, and no learner needs to.
