As a language learner, do you have to know all these words? Probably not! In fact, an educated native speaker is reported to know around 16,000 to 20,000 word families. A word family is a group of words that share common features, such as sound and meaning. For example, a word family for “argue” includes argue, arguing, argues, argued, arguable, arguably, unarguably, argument, and arguments.
Realistically, how many words do you need to know to be a competent English user? Below, you’ll find an answer to this question.
If you wish to read a wide variety of texts (e.g., novels, newspapers, blog entries) and recognize 98 percent of the words in the texts (98 out of 100 words), you’ll have to know around 8,000 to 9,000 word families (or around 35,000 individual words). This means that you need to know a lot of vocabulary to read a text. If you are a student in a university where English is widely used, this must be your goal.
Vocabulary size required to watch movies and TV programs in English is different from what is required for reading. In order to know 98 percent of the words in movies in English (e.g., Shrek, Frozen, The Hunger Games), you need to know around 6,000 word families. For TV programs (e.g., Friends, BBC News), you need to know around 7,000 word families.
Whether you read books or watch movies and television in English, you need to be familiar with proper nouns. These nouns include company names (e.g., Google, Samsung), names of people (e.g., Mandela, Obama), and names of places (e.g., Minneapolis, Disneyland).
Here at the end, I’d like to point out that the number of English words you must know also depends on your learning goals. If you want to earn a law degree or do crossword puzzles in English, you probably need to know a much larger vocabulary (more than 10,000 word families). So, it always depends.
Source: English Club