Zipf's Law and the 80/20 Rule of Vocabulary
The mathematical distribution that simplifies language learning.
In 1935, Harvard linguist George Kingsley Zipf noticed an astonishing mathematical constant in human languages: the frequency of any word in a corpus is inversely proportional to its rank in the frequency table.
The most common word occurs twice as often as the second most common word, three times as often as the third, and so on. In practical terms, this means an extraordinarily small core of high-frequency words dominates almost everything people say.
Vocabulary Thresholds by CEFR Level
What official international frameworks require for each stage of fluency.
The Common European Framework of Reference for Languages (CEFR) maps vocabulary sizes to functional ability:
• A1 (Complete Beginner): 500 words. Can introduce yourself and order coffee.
• A2 (Elementary): 1,000 words. Can handle basic travel situations and routine conversations.
• B1 (Intermediate): 2,000 words. Can express opinions, describe events, and understand the main points of clear speech.
• B2 (Upper Intermediate): 4,000 words. Can converse spontaneously with native speakers and understand complex texts.