Kanshudo's Guide to Prioritizing Japanese Vocabulary

How to prioritize Japanese words to study

Which Japanese words should you learn? How many do you need to know? In this guide we will show you how to decide what Japanese words to study to give you the best chance of success. We'll show you how to use Kanshudo to study the most useful words in Japanese.
We introduce our scoring system for the 'usefulness' of every Japanese word, which is a measure of how important the word is for you to learn. Our usefulness scores are based on the most comprehensive analysis ever performed of how Japanese words are actually used in the real world.
Prioritizing your studies by usefulness is the best way to prioritize your study of Japanese vocabulary. In this guide we'll give you everything you need to know.
1. How can I decide which Japanese words to learn?
Learning a new language can be overwhelming: often it feels as if there is just so much to learn. For Japanese, the problem is compounded by the complexity of the writing system, which makes it significantly harder for learners to read, which is one of the most useful tools for learning anything.
The key to success in learning anything is connecting it with what you already know and using it repeatedly. So the best way to prioritize vocabulary is to learn words you will encounter most often wherever you personally use Japanese. If you are using a textbook, it's best to learn the words in the textbook, because textbooks are designed to keep using the same words.
However, if you encounter Japanese in your daily life, it is better to focus on words that actually come up in your daily life - they will be more relevant to you than textbook words, and so you will find it easier to learn them. Plus, knowing the words you actually encounter in real life will help you communicate better, which will further increase your ability to engage and learn.
Kanshudo can help you with this, as we have prioritized every word in our system according to where and how often it's used. Read on to find out how we did it and how it can help you.
2. Kanshudo Usefulness Level for Japanese words
Whatever your personal situation, the Kanshudo Usefulness Level provides an intuitive and effective way to prioritize words for your studies. The Kanshudo Usefulness score (and level ranking) is based on (we think) the most comprehensive analysis of usage of Japanese words ever undertaken. We have assigned every word in Japanese a score we call 'usefulness', which is a composite of many different factors, detailed below. Then, we have ranked every word in order of descending usefulness, and classified them into levels. For example, the top level, Kanshudo Usefulness Level 1, contains the 500 most useful words in Japanese. For almost any student of Japanese, these are the most useful words to learn first.
To come up with usefulness scores, we looked at the following criteria:
  • Google count: how many times does the word appear in Google search results. This provides a very simple classification of how popular a word is in written text of many kinds.
  • Google exact match count: how many times the word appears exactly in Google search results. This helps to distinguish words which are composites or variants of other words.
  • The characters in the word. Words that use only hiragana, katakana or Joyo kanji get higher scores; words which use Hyogaiji or Jinmeiyo kanji, or non-Japanese characters, get lower scores. Words that use more common Joyo kanji score more highly than words that use less common Joyo kanji.
  • Grammar: words that function as key grammatical constructions score more highly.
  • JLPT level: words that are listed in the Wikipedia JLPT lists score more highly. Easier levels (N5) score more highly than harder levels (N1).
  • Wikipedia: words that appear most commonly on Wikipedia score more highly. We used the Wikipedia 20,0000 analysis of the most common words on Wikipedia.
  • EDICT frequency level: words that are assigned a frequency code in the EDICT open source dictionary score more highly. Lower frequency bands (more common words) score more highly.
  • Ichimango: words that appear in the 'Ichimango goi bunruishuu' frequency list (Senmon Kyouiku Publishing, Tokyo, 1998) score more highly.
  • Routledge: words that appear in the Routledge 5000 vocabulary list score more highly.
  • iKnow: words that appear in the iKnow! 6000 vocabulary list score more highly.
For any word, you can get detailed information about how we came up with its usefulness score by looking at the word details page (click on the word in search results, then click on DETAILS VIEW). For example, see the details page for 時間.
Based on usefulness score, all words are classified into levels as follows:
Level Words in level Cumulative words Badge
1 500 500
2 1,000 1,500
3 1,500 3,000
4 2,000 5,000
5 5,000 10,000
6 5,000 15,000
7 5,000 20,000
8 10,000 30,000
9 20,000 50,000
10 50,000 100,000
11 50,000 150,000
12 30,000 180,000
Words with usefulness levels 1-9 are shown with a badge next to them in search results so you can quickly see how important they are to learn. Many useful words have multiple forms, and less common forms have a badge that looks like this:
3. Words with multiple forms or multiple readings
One tricky aspect of Japanese is that many words (with the same pronunciation and meaning) can be written in several ways, and a given written form of a word can often be pronounced in different ways. Which reading should you learn? Which form of a word should you learn? Kanshudo makes this very easy.
For all words with multiple readings, we show you the most common one by default. If you click on the word, you will see details of additional readings. For example:
1. important; valuable; serious matter
2. safe (Tochigi dialect); OK  (see also: だいじょうぶ; this meaning is restricted to reading だいじ)
(click the word to view an additional 1 reading, examples and links)
For all words with multiple forms, the usefulness badge appears in faded colors to show you when you are not looking at the most useful form. For example, here's how 御金 (a less common form of お金) appears:
Most common form: お金
money  (see also: ; polite (teineigo) language)
(click the word to view an additional 2 forms, examples and links)
Many words have multiple readings and multiple forms. You can see information about all variants just by clicking the word itself (in the green box). For example:
watch; clock; timepiece
(click the word to view an additional 1 reading and 2 forms, examples and links)
4. How many words do I need to know?
This is a great question! This is perhaps the most important and yet most-nearly-impossible-to-answer question of all questions about learning Japanese, after perhaps the hardest of all ('how long will it take me to learn Japanese?'). We have researched this question in some depth, and here are our conclusions:
  • If you want to be able to have very basic conversations, enough to get around and enrich your time in Japan with simple communication, around 500 words is more than enough. (If you are in this situation, you are best learning simple sentence structures, along with hiragana and 100 or so kanji. Start with our Beginner Lessons which will get you to and beyond this level.
  • About 3000-5000 words will give you 'basic fluency'. At this level you will be able to find a way to say anything you want to, but it probably won't be the way a native speaker would say it. You will have no trouble communicating and navigating in daily life, but you will need a dictionary to read most written material. This vocabulary corresponds with JLPT levels N3 / N2.
  • About 10,000 words will give you a high level of competence. You will still need to look up a lot of words if you read a novel, but you will be able to get the gist of almost anything you read or hear. This level will get you an easy pass in the highest level of the JLPT, and will enable you to function in an exclusively-Japanese academic or work environment. If your focus is conversation rather than reading, this level will probably suffice for fluency.
  • Around 30,000-50,000 words will give you native level reading proficiency, equivalent to a college-educated Japanese. Of course, this level is only attained by a tiny fraction of non-native Japanese speakers. This level is somewhat higher than the equivalent for English, partly because of the number of variations introduced by multiple readings and greater prevalence of compound words, and partly because the nature of kanji actually makes it much easier to 'construct' a word from its parts, where in English you would need to know a separate word. For example, the word 自動 (じどう) means 'automatic'. In English, you would need to learn this word. In Japanese, it is easy to construct from the very common kanji 自 (self) and 動 (move).
If you are interested, please see the Further reading section for our sources.
So the question is really: what are your goals in learning Japanese? Depending on how you see yourself using Japanese in your life, you can decide on a target. Whatever your target, you need to start with words suited to your current level - read How do I use Kanshudo to study words at my level for details.
5. Should I learn words with lower usefulness levels?
When you read a newspaper article or novel, you will quickly notice that you encounter words with a usefulness level lower (i.e., a higher number) than 9, which implies they are not within the most useful 50,000 words in Japanese. 'Hold on!', we hear you say; 'If 30,000 words is all a native Japanese would know, why do I need to know words that are less useful than that?!'.
This is a great question, and the answer is 'you may not ... or you may'. In general, if words are not commonly used, then you probably don't want to spend time learning them unless you are going to be needing them. However, your personal definition of 'useful words' is going to be specific to you. If your favorite newspaper or a friend uses a word a lot, that would be a great reason to learn it. It's entirely possible a word is 'common' from your perspective, but not common in real world settings.
It's very possible that as your Japanese progresses, you won't need to 'learn' the less common words, because you will understand them. Compound words are a great example of this. For example, 分かつ meaning 'to divide' is a common word. 与える meaning to 'allot' is also a common word. 分かちあたえる means 'to apportion to', and is much less common - but there's no real reason to learn it, because its meaning will be relatively clear when you know the root words well.
There are also words that are included in the collections we analyzed that are not especially common in the real world, but may be necessary for you to learn because they are important for a certain setting. For example, the JLPT collections include words that are not especially 'common' in daily life, but are considered 'important' by the creators of the test, and as a result we prioritize them over other words that are more common. We have found examples of this issue in every one of the lists we have analyzed, and tried to adjust the relative contributions of the collections to the total scores to reflect their relative importance to most students of Japanese.
Although Kanshudo's dictionary includes nearly 260,000 entries, about 80,000 of those entries are variants of the same word. Of the 180,000 or so distinct 'words', many are actually compound words that have an independent meaning. In our scoring, we rank these compound expressions as having a lower usefulness than the words that form them, because you will probably not need to 'learn' them independently.
A simple example from English would be idioms, such as 'to cost an arm and a leg', which uses three key terms (cost, arm and leg) that are individually very common. Once you know the individual terms, you probably don't need to actually spend time learning the phrase - you will just absorb it. We apply the same principle in our classification of Japanese terms - our usefulness lists generally prioritize 'core' words, not compound phrases (although there are plenty of exceptions).
In Japanese, 的 (てき) is commonly added to nouns to denote the idea of being 'like' the noun. In general, we consider this just a derivative version of the original noun that you would understand implicitly. In other cases, the derived form is more common - for example, 自動 (じどう) means automatic, but actually is more commonly encountered as 自動的 (じどうてき), which would be translated the same way. In some situations, the variants have somewhat distinct meanings, and they might both be ranked. For example, 積極 (せっきょく) means 'positive' or 'progressive', but it is just as commonly encountered as 積極的 (せっきょくてき), which means 'proactive', so both have high usefulness scores.
6. How do I use Kanshudo to study words at my level?
You can use usefulness scores to prioritize your studies in several ways:
  • You can see usefulness scores next to every word when you use our dictionary search - just go to Search and look up a word. Usefulness scores of 9 or less appear in a badge next to the word. Lower scores, as well as the frequency data that led to the usefulness score, can be seen by clicking through to the details page.
  • Use our vocab Usefulness Collections - the most useful 10,000 words in Japanese are conveniently displayed in order, so you can study based on your level.
  • Quick Study - you can create a quick study set using vocab with a specific usefulness level. As you study, you can immediately add any cards you don't know to a flashcard set for more in-depth study.
  • When you study Flashcards in any set, you can choose to prioritize cards by usefulness. Kanshudo will automatically create study sets with the most useful cards in the collection first. This is a highly effective way to study!
  • Play Word Match - a fun way to test and expand your vocabulary. Word Match lets you focus on words within a usefulness range.
We are working on more great new ways to focus your vocabulary studies, and we are updating the whole system to take advantage of our usefulness data. We'll update this section as we introduce the changes.
A very important question to think about is how many words to study per day. We have been gathering data on this question based on observing our users who make the most progress, and we will be sharing the results in a future article!
7. Further reading
To read more about vocabulary sizes, see:
Kanshudo is your AI Japanese tutor, and your constant companion on the road to mastery of the Japanese language. To get started learning Japanese, just follow the study recommendations on your Dashboard. You can use Quick search (accessible using the icon at the top of every page) to look up any Japanese word, kanji or grammar point, as well as to find anything on Kanshudo quickly. For an overview, take the tour.