Vocabulary Size Estimate Calculator
Estimate your vocabulary size in a foreign language from a simple test score.
Compare your word count to conversational, fluent, and native benchmarks.
How vocabulary tests work
Asking “do you know all 100,000 words in Russian?” is impossible. Vocabulary tests sample. They give you a list of, say, 50 words drawn from across the frequency spectrum, ask which you know, and multiply: if you knew 35 out of 50, you know roughly 70% of the language’s vocabulary.
The simple formula:
estimated_size = (words_known ÷ words_tested) × total_language_vocabulary
This gets noisier with small samples (50 words is a rough estimate; 200 words is solid). The best public tests (TestYourVocab, LexTutor) use frequency-graded samples so the score actually means something. Random word lists from a dictionary do not work; you need the test to weight toward the words you would actually encounter.
How big is a language?
Working numbers for “active words” used in normal modern adult speech and writing:
| Language | Total active vocabulary | Educated native |
|---|---|---|
| English | ~170,000 | 20,000 to 35,000 |
| Spanish | ~93,000 | 15,000 to 30,000 |
| French | ~135,000 | 20,000 to 30,000 |
| German | ~135,000 | 20,000 to 35,000 |
| Mandarin (characters) | ~50,000 | 6,000 to 8,000 unique |
| Russian | ~150,000 | 25,000 to 35,000 |
Educated natives use a fraction of the total. Most of those 170,000 English dictionary entries are archaic, technical, regional, or proper nouns.
The 80/20 reality of vocabulary
This is where the curve gets interesting. Research by Paul Nation and others measures word coverage of typical text:
| Vocabulary | Text coverage |
|---|---|
| 1,000 words | 72% |
| 2,000 words | 80% |
| 3,000 words | 84% |
| 5,000 words | 88% |
| 8,000 words | 93% |
| 15,000 words | 97% |
| 20,000 words | 98% |
The first 2,000 words give you 80% of any text, which is why beginners can survive simple conversation quickly. The push from 95% to 98% comprehension takes roughly ten times more vocabulary effort. Real reading without a dictionary needs 98% coverage; anything less and you are stopping to look up something on every page.
What this means for study
For practical fluency, target 5,000 to 8,000 words. That covers casual reading, all conversation, and most TV with subtitles. Going past 15,000 is a slow grind that mostly pays back in literary reading and academic writing.
Spaced repetition (Anki, Memrise) is the most efficient vocabulary-acquisition method known. 10 to 20 new cards a day for a year gets most learners to the 5,000-word level on a Category I language. Doubling that pace tends to break learners within a few weeks; consistency beats intensity here.