Once you get past learning hiragana - your あ、い、う、え、and おs - you might be wondering just how many words you have to learn in order to be fluent in Japanese. After all, think about how many words you might know in English!
Don't worry! In this post, we'll be going over all of the information you need to know about reaching fluency in Japanese!
Defining Native vs. Fluent
First, we have to define what it means to be fluent in any language. This definition will partially depend on your personal goals and what you want to achieve. Some people are content just learning enough to get around Japan, while other people want to speak as well as a native.
Unfortunately, if you're in the latter, some research studies suggest that even the most proficient second language (L2) learners may struggle to meet the level of a native speaker.
A word family is a base word plus all of its derived forms. For example, if the base word is "depend," then "dependent" and "dependable" would be part of its word family
Most adult native speakers have a vocabulary exceeding 10,000 word families. This number increases based on age and education. A 60-year old will know, on average, a little over 3,000 additional word families than a 20-year old. Level of education also seems to have an effect. Someone who has completed a PhD will know more word families than someone who hasn't.
If you learned 10 word families a day (that means a single word plus a majority of its derivatives), then it could take you a thousand days to get to where a native might be. But even then, there's still another factor that plays a role in native fluency vs. learned fluency.
That factor is L1 language acquisition. When we're learning our first language, part of the process is based on intrinsic factors. We learn languages better at a young age, and we pick up things like accents faster. This innate ability drops off the older we get.
Also, language is more than just words and grammar. It's about communicating. There are sociocultural factors that also play a roll in native-level fluency. Some of these may be as simple as a feeling which is hard to describe in one language but has its own word in another. Maybe it's a reference that has been lost to time, but the native speaker still understands its underlying meaning. Or perhaps it's tied to a custom that non-native speakers might not be familiar with or understand on the same level as a native speaker.
Setting Realistic Goals
It's really important to understand a critical factor on the topic of fluency. You don't need to be "native-level." You just have to reach your own goal. So, if you felt discouraged by the points above, don't lose hope!
Obviously, there are plenty of highly fluent people in the world who use their L2 well enough to the point that even native speakers might not even notice a difference.
Let's look at fluency in the partial context of proficiency. Proficiency measures how well you can use and interpret a language. We'll put a scale from 0% to 100%, where someone who can't use another language at all and recognizes none of the words would be at 0. Someone who knows every single word ever (which is arguably impossible, even for native speakers) would be at 100%.
Now, we can look at this scale in terms of fractions. So, if I was 90% proficient in a language, I would understand on average 1-in-every-10 words.
What does that even look like? The paragraph below is what ~75% (3-in-4 words) proficiency is in English.
Attention all panegin. The 9:00 roind service rtoin is arriving on palnnon ten. Please wait behind the tiynnin line and allow panegin who are on the train to step off before boaingn. From June 1st to July 10th, the nonn service to dontniwn will be running on a limited schubn due to low caprnon. We apologize for the ingonfin. Starting July 1st, all panegin will be required to use a moubn pass. You can dpknorn the metro pass aogn on your smfubon device. If you would like a phnsin card, please talk to a station atninrn. We thank you for your corepinan.
Now here's 90%.
Attention all passengers. The 9:00 roind service train is arriving on platform ten. Please wait behind the yellow line and allow passengers who are on the train to step off before boarding. From June 1st to July 10th, the local service to dontniwn will be running on a limited schedule due to low capacity. We apologize for the ingonfin. Starting July 1st, all passengers will be required to use a metro pass. You can download the metro pass aogn on your smfubon device. If you would like a phnsin card, please talk to a station attendant. We thank you for your corepinan.
As you can see, that 15% makes a huge difference!
In general, a good goal for understandable fluency is 95-98%. At that level, you would only miss 1-3 words in that entire paragraph. Some people say it's okay to go lower, while others say you should go higher than this. At the end of day, it still depends on your personal goals.
Of course, we also assume that this fluency applies to your daily life interactions in Japanese. When it comes to complex topics with unique vocabulary, you should expect your fluency to drop unless you've learned the words associated with that topic. Would you use 2度不完全房室ブロック (second degree incomplete atrioventricular block, a type of irregular heartbeat) on a daily basis? Unless you're a medical student looking to become a doctor in Japan, probably not.
Putting Numbers to Fluency
Now that we've established a baseline expectation for fluency, it's time to finally use what we've learned to put some numbers down.
The easiest way to look at fluency is through number of words. This is because there's some existing research on this topic specifically for Japanese language. One study analyzed comprehension based on medium (magazines, newspapers, books, internet forums, etc.). When you combine all of the sources and parse the average, you get ~11,100 words for 95% and ~22,900 for 98%.
Matsushita, 2012. Please note that in calculating the averages above, only the magazines, newspapers, and VDRJ databases were used. Internet forum sites and books were excluded because the VDRJ already includes both books and internet forum sites.
But you might be thinking...that's a huge jump for 3%!
And here we come to the other factor influencing language learning. Vocabulary acquisition isn't linear, it's logarithmic. The closer you get to 100%, the more words you need to learn in order to make the same amount of progress.
This is because we use certain words more frequently than others. The top most used English words are things like "be," "I," "you," "a,"and so on. It's definitely not "second degree incomplete atrioventricular block."
This can seem demoralizing, but in reality it can be a good thing. It means that when you're starting out and building your language learning habit, you'll make a lot of progress for every word you learn. And over time, you'll be able to use that habit to get to 95%-98% comprehension.
Of course, if you need a little extra help along the way, Virtual Nihongo offers lessons for students. If you're interested, check out our Course & Tutoring page for more information. We'd love to support you on your language learning journey!
References
Brysbaert, M., Stevens, M., Mandera, P., & Keuleers, E. (2016). "How Many Words Do We Know? Practical Estimates of Vocabulary Size Dependent on Word Definition, the Degree of Language Input and the Participant’s Age." Frontiers in Psychology, 29(7). https://doi.org/10.3389/fpsyg.2016.01116.
Matsushita, T. (2012). "In What Order Should Learners Learn Japanese
Vocabulary? A Corpus-based Approach." https://openaccess.wgtn.ac.nz/articles/thesis/In_What_Order_Should_Learners_Learn_Japanese_Vocabulary_A_Corpus-based_Approach/17011514.