Why You Can’t Gauge Fluency by Counting Vocabulary Words

By OptiLingo Team • 18 minute read

How Many Words Do You Need to Be Fluent in a Language?

Many language learners believe that once they have acquired a certain number of words, they can consider themselves fluent. When I was starting my language learning journey, I was obsessed with this idea. If only I knew the 500 most common words… the top 2,500 most common words…. the top 5,000… I’d be fluent, right? So, how many words does it take to be fluent? Turns out, word count means little when it comes to learning a foreign language.

The Problem with Word Count and Fluency

Asking, “how many words to be fluent?” is problematic. Counting words is an inefficient way to evaluate fluency. There are several reasons for this:

  1. It’s impossible to come up with an exact number of words that demonstrate fluency.
  2. Language experts disagree about how to measure vocabulary size.
  3. When it comes to learning a language, all words are not equal. Some words are more valuable for people to learn than others, and the order in which we learn words matters.

There are much better ways to measure progress. It starts with examining the relationship between the learning individual words and learning a whole new language. How many words do you need to know to be proficient in a language? Spoiler alert: Experts disagree. They also don’t share consensus on what constitutes a word or what it means to know a word.

What Is a Word?

You might assume everyone means the same thing when they talk about a word. But, that’s not the case at all. Language experts sharply disagree with each other about how many words people have in their vocabularies. For example, one expert says the average native English-speaking high school graduate knows at least 35,000 words. Another expert says the average highly-educated native English speaker has a vocabulary of 10,000 words.

It doesn’t make sense that people with more education would have smaller vocabularies than people with less education. Where does this discrepancy come from?

The variance in the numbers shows how experts measure these concepts differently. They don’t agree on the definition of “word” or the definition of “know”. As a result, it’s not surprising they come up with such contrasting answers.

Some experts count every form of a word as a separate word. For example, they count each form of the verb “to see” separately. By this measurement, “to see,” “see,” “sees,” “seeing,” “saw” and “seen” would be considered six individual words. These experts apply the same logic to nouns, counting “cat” and “cats” as two separate words.

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Other experts count only the root word, not its different forms. As a result, they come up with much smaller numbers. These experts count “to see,” “see,” “sees,” “seeing,” “saw” and “seen” as only one word because they are all forms of “to see.” They also consider “cat” and “cats” as a single word, because the singular and plural are forms of the same root noun.

Their thinking is that when people learn a root word, such as “to see” or “cat,” they are learning a new word for the first time. However, when the same people then learn different forms of the root word, such as “seeing” or “cats,” that should be considered an addition to their knowledge of grammar instead of an expansion of their vocabulary.

After all, these experts say, this is how we learn languages. First, we learn one form of a word. Then, as we understand more about the structure of the language, we generalize the use of the word to other situations using its other forms.

When evaluating the number of words in people’s vocabularies, the experts who count every form of a word will come up with a much higher word count than will the experts who count only the root forms. And that’s the case even when both sets of experts are studying the same language and the same groups of people.

What Does It Mean to “Know” a Word?

Experts also disagree on when a person actually knows a word. People who study languages make a distinction between active vocabulary and passive vocabulary. Some think people “know” a word only if it is in their active vocabulary. Others believe that people “know” all the words in their active and passive vocabularies combined.

A word is in your active vocabulary if you can remember it quickly and use it without hesitation. In your thoughts, speech, and writing. A passive vocabulary word is one you can recognize and more or less understand when you happen to hear it or see it. However, you can’t easily remember the word and aren’t comfortable using it in conversation. For both native and non-native speakers, the number of words in their passive vocabularies is usually several times larger than the number of words in their active vocabularies.

People generally absorb a new word into their passive vocabularies after they see or hear it the first few times. Then, as they encounter the word more often and better understand its context and different meanings, it becomes part of their active vocabulary. (One of the best ways to learn a language is to move words from your passive into your active vocabulary.)

Here’s the problem: When trying to figure out how many words a native speaker knows, do you count their active or passive vocabulary? That’s why asking, “how many words to be fluent” is quite problematic.

Are Vocabulary Ranges Better Than Word Counts?

For the purpose of this discussion, we’ll measure vocabulary by counting only root words (not their different forms). We’ll also only count the words in people’s active vocabularies. This is the approach taken by the Common European Framework of Reference for Languages (CEFR).

The CEFR is the current guideline used to describe achievements of learners of foreign languages across Europe and, increasingly, in other countries. It was put together by the Council of Europe as the main part of a project called “Language Learning for European Citizenship” between 1989 and 1996. The CERF’s main aim is to provide a method of learning, teaching, and assessing that applies to all languages in Europe.

The six reference levels (see below) are becoming widely accepted as the de facto standard for evaluating an individual’s language proficiency.


Using this method of measurement, we can sort people based on their language fluency into six groups or levels. You may have seen this table before, but we’ll present it again here for convenience.


Speakers generally can:
500 words
Use and understand basic phrases when speaking slowly.
1,000 words
Understand simple expressions and express immediate needs.
2,000 words
Understand common issues and improvise discussion.
4,000 words
Understand complex topics; engage in spontaneous speech.
8,000 words
Express ideas fluently and spontaneously without strain.
16,000 words
Comprehend virtually everything read or heard.

Looking at these ranges, you may say, “Well, I’d like to aim for level A2 before my trip to Spain next year.” Great, you’ve clarified your goal. But now what?

How to Study Foreign Language Vocabulary

How do you choose the most efficient way to learn the vocabulary words you need to achieve your goals? Here’s my recommendation.

Step 1: Decide What Type of Vocabulary You’ll Learn

Imagine waving a magic wand and having any learning materials you wanted to be delivered to you instantly. That’s the perfect world. You would start by deciding what kind of vocabulary you wanted to learn. This might sound trivial, but it’s more nuanced than you might think.

  • Are you flying to Germany for a trade show on industrials? You might want to focus on highly specialized, technical vocabulary to understand what people are discussing.
  • Do you work at a hospital with a large Russian-speaking community in Brooklyn, New York? Focus on basic anatomy and words that describe major medical issues.
  • Are you an accountant who works in a large Spanish-speaking community in Los Angeles? Focus on vocabulary that deals with math, numbers, and tax issues.

Of course, these are specialized use cases. It’s more common that language learners want to pick up general-use vocabulary. So, while your approach would definitely differ in the examples above, let’s assume you’re a general-interest language learner.

Step 2: Create a Vocabulary List

Even if you’re a general-interest language learner, there are a number of different kinds of vocabulary lists from which you might want to choose.

Sight-Words Lists

For example, you might start with something called sight words. These are very basic words often targeted at young children. Most of these words are concrete and cover a narrow range of topics. Common sight words include words like the following: mother, father, dog, cat, tall, short, eat, cry, play, sleep.

As you can already see, these are very basic words, but they are as valuable to an adult language learner as they are to a native-speaking child. Sight-word vocabulary lists range from 50-250 words. While sight-word lists are very common for English, they are not always easy to find for other languages. You can typically find free word lists with some Internet research.

Travel-Word Lists

Alternatively, you might want to pick up common travel words. These are lists that can easily be found in a variety of travel-phrase books, and they cover a much broader range of vocabulary. There is a greater emphasis on more abstract terms, like “justice” or “political system.” These words are difficult to convey through an image. Travel-word lists are typically much deeper in their scope, even if that means they cover words that are not all that common.

For example, the food section of a travel-word list might include words for lobster, muscles, clam, and tartar sauce. While I’m sure you know these words in English, you probably wouldn’t use any of these words as often as the word “breakfast.” In fact, you could replace most of these words with “seafood.”

Travel-word lists can be found in any number of travel-phrase books. However, it’s rare for phrasebooks to provide them all in list form. More often, they are spread throughout the book, so it can be difficult to extract them.

Word-Frequency Lists

Finally, you can try taking advantage of word-frequency lists. Lists like these are somewhat easy to find for widely-spoken languages and almost non-existent for languages with fewer native speakers. The reason for this is simple: such lists are difficult and time-consuming to produce.

English word-frequency lists, for example, are produced every few decades by researchers. They gather a large sample of text in print, video, and audio across a range of subjects. Next, they data-mine the words and rank them in frequency. A similar process is followed for other languages, but it requires plenty of content in lots of media and numerous people to data-mine them. That’s why lists like these are less common for languages that are not as popular.

You can purchase word-frequency lists in book form from a variety of publishers. There are several open-source lists freely available on the web. Go with the free list. Most lists range from 1,000 to 10,000 words, providing at least 5,000 of the most common words.

The reason I suggest going with a free list is simple. If you’re an academic statistician, you may really need to know whether the word for “mom” is more frequently used than “dad.” You might also wonder whether the more formal “mother” is more or less common than “mom.”But if you’re an average language learner, none of this matters to you. You just need the words.

What If Your Word List Doesn’t Exist?

I’m always surprised by the lack of effort to create a helpful-word list. Here’s an example: in every English word-frequency list I’ve ever seen, “the” is at the top of the list, in position #1 or #2. The next entry is “a,” which trades the top spot with “the,” depending on the list. While “a” and “the” are frequently used words, they are not especially helpful.

You could learn everything in the English language other than definite and indefinite articles and still be 100 percent understood by native speakers. Think of a classic spy movie: “I detonate bomb now, Mr. Bond!” Does the lack of “the” before “bomb” confuse Mr. Bond? Clearly not.)

Step 3: Begin to Study Words

Once you’ve selected your word list, it’s time to dig in (with some caveats).

Vocabulary Variety Is the Spice of Life

Make sure your word list covers a range of parts of speech, including nouns, pronouns, adjectives, verbs, adverbs, etc. This will help you build basic sentences as you expand your vocabulary. If you spend too much time just memorizing a group of words like, fruits, for instance, you’ll have a hard time trying to tell someone that you’re hungry.

Word Similarity Can Be Spicy, Too

While you’re at it, you might also want to see if you can figure out whether the language you’re learning has any cognates in common with English. What are cognates? These are words common between two languages. Sometimes they are spelled the same. Other times they are pronounced the same.

It’s rare that they are both spelled and pronounced exactly the same, though. Words like “Internet” or “coffee” or “metro” are cognates commonly shared between many modern languages. At the same time, you’ll also want to be wary of “false friends.” These are words spelled or pronounced similarly between languages but have very different meanings.

Method Counts

You might be tempted to study vocabulary by reading words out loud, writing them down, labeling a bunch of things in your home with Post-it notes, or building flashcard decks, either in real life or with apps. None of these are bad approaches. But remember the difference between learning and studying. Both can be important. However, studying is not the same as learning. (Anyone who has ever studied for a test only to fail the final exam knows this all too well.)

While you can and probably should try some of these methods, you should also attempt to learn your vocabulary by learning the words in context. This requires the use of common phrases and basic sentences.

Learning Words in Context

Learning words in phrases and sentences is one of the most widely-used methods successful language learners use to build a large vocabulary quickly. Variations of this approach are sometimes referred to as “mass input.” This is really just a real-world application of the Input Hypothesis developed by Stephen Krashen, which I covered earlier.

Another real-world application of this approach is called “sentence mining,” or the “10,000-sentence approach.” Adherents to this method simply expose themselves to 10,000 sentences translated between English and their target language. There is no active attempt to memorize, just to comprehend.

The idea is that with a large enough sample of sentences, the language learner will naturally develop a significant vocabulary and intuitive sense of the grammar of a language.

Guided Immersion

Each of these approaches is excellent and just variations on one another. My own method, Guided Immersion, which I cover in a later section, is an evolution on this theme. I’ll spare you the details right now, but here’s the summary of how my method works. Guided Immersion uses a much smaller data set than 10,000 sentences. However, it does less with more.

I don’t want to come off sounding like my method is “the best.” I think it’s pretty nifty. But as I’ve said countless times before, what works for one person may not work for another. I genuinely believe every language learner should draw from a wide range of learning materials.

Getting back to the original topic, you can study your vocabulary using any study method you want. There is a time and place for active, conscious study for lots of language learners. But if you want to really learn new vocabulary so you can make use of it in everyday discussion, any variation on Krashen’s Input Hypothesis will work, so long as:

  • You have a reasonably good quality collection of words, statements, phrases, or even short stories.
  • Those materials are available in your target language and you can understand their meaning in English (or your native language).
  • You have a reasonable volume of materials and you spend a realistic amount of time reviewing those materials.

Have Fun While Learning Words

One final note here. I’ve mentioned before that your language-learning efforts should be relevant, engaging, fun, and within the context of what you want to learn. I’ve seen many (struggling) language learners focus almost exclusively on the study of a language.

Eager new language learners sometimes spend hours per day slogging through textbooks, unable to move on to the next chapter until they have memorized 90 percent of the material covered. It’s not effective or enjoyable. And that means you’ll eventually burnout. This isn’t how human beings learn languages. It’s OK to use a textbook. But, it might be better to read short stories.

It’s just that there are so many ways to learn a language. It’s fine to play video games, listen to the radio, work with a tutor, or watch YouTube videos. As long as you’re exposing yourself to a broad range of inputs and enjoying them, you’ll learn the language. If you just narrow in on a list and try to memorize it, you won’t.

Don’t Focus on Memorizing Definitions

Many people begin their language studies by attempting to memorize high-frequency words and their definitions. Adherents often focus on the first 500–1,000 most-frequently-used vocabulary words in their target language.

There’s nothing wrong with that; I’ve used this approach with several of the languages I’ve taught myself. But if this is an approach you’re considering, give careful thought to where you get your vocabulary lists and how they were created. Go back to our exploration of “what is a word” and consider how you choose to study definitions.

You don’t need to memorize every definition of the words you are learning. That would be very time consuming because some common words have several alternative definitions. For example, in English, the word “murder” normally means “to kill.” It is a word one often encounters in news reports. An alternative definition is “a flock of crows.” This second definition is not commonly known among native speakers, let alone language learning students.

Instead, it is far more efficient to learn only a few of the most common definitions. Specifically, learn the ones you are likely to use in ordinary conversations. And with experience, you’ll naturally learn more when you hear the words used in different contexts. In that way, through exposure to the language over time, you’ll assimilate the language, learning it in a natural way.

If you focus on learning the most widely used words with their most commonly used meanings, you’ll pick up the language far more efficiently than if you tried to take in everything at random.

How Many Words to be Fluent?

There is no precise number of words you need to know to become fluent in a new language. In part, that is because language scholars use different measurements when they count words and apply different standards to evaluate what it means to know a word. It’s more useful to group people by their language proficiency according to a rough estimate of the number of words.

When it comes to learning a language, all words are not equal. Learning some types of words will accelerate your progress more quickly than other types of words. To be most effective in learning a language, focus on the most common words in that language before starting to study a more specialized vocabulary. And learn the most common definitions first, instead of trying to memorize every definition.

You’ll progress the fastest if you start by spending your time learning what you can use right away. If you try to read a dictionary from cover to cover instead you’ll meet challenges. Gasping every word and every definition in the language is inefficient and most likely will result in wasting your effort. (I know because I tried – and failed – using this method. It’s mind-numbing and horribly inefficient.)

Learn the Most Common Words and Phrases

Learning the most common words and definitions puts you in a position to start assimilating the language in a natural way. The more you hear and read words in the language, the more you understand new words and new meanings from their context and other relevant cues. This is similar to the way you learned your first language as a child. The more you expose yourself to your new language, the more fluent you’ll become.

You don’t need to count the number of words you learn in order to become fluent. Instead, put your time and effort where they will do the most good. Speed up your language learning by focusing on the most commonly used words, and let your natural language-learning ability take over.

This combination of targeted studying and assimilating language by experience is the most powerful and efficient way to master a new language.

OptiLingo Team