Japanese Potential Form: How To Say “Can” And “Can’t” In Japanese

Once you’ve dipped your toes into the waters of learning Japanese, you may find that a lot of new grammatical constructions come at you quickly.

From conjugating verbs, to sentence order, and learning the Japanese potential form, it can be a lot to take in at the beginning. Thankfully, Japanese is built so that over time, the more you know, the easier it is to learn more.

But you might have noticed that you can’t quite express exactly what you want to say yet; for many people, that happens most often when they want to switch from saying “No, I don’t do that” to “No, I can’t do that” for the first time.

Being able to describe what you can and can’t do in Japanese is one of the bridges that will take you from a beginner speaker or writer to a more intermediate level. But don’t be overwhelmed!

The Japanese potential form is simple to learn and very consistent. With just a little bit of practice, you’ll be wrapping this grammatical construction into your everyday usage in no time.

Building The Japanese Potential Form

When you say “can” or “can’t” in Japanese, you’re using the Japanese potential form.

In other words, you are describing your potential to do or not do something. Sometimes you have the potential, and you can do it just fine, and other times, no way.

Building the potential form in Japanese is simple because it relies on verb types, and there are only two in Japanese: ru-verbs and u-verbs.

You’ve likely already learned a bit about the Japanese verb conjugation rules and how ru verbs and u verbs work, because you also need this information in order to conjugate verbs at all.

Remember that a ru-verb is conjugated by removing the ru and adding –masu (or whatever ending you need), whereas a u-verb changes the u (or rather, the u-sounding hiragana, like ku or mu or tsu) to another vowel.

Let’s see some examples of ru-verbs:

• Taberu 食べる (to eat) > Tabemasu
• Neru 寝る (to sleep) > Nemasu

As you can see, just chop that ru off and add your ending. Now take a look at u-verbs:

• Utau 歌う (to sing) > Utaimasu
• Oyogu 泳ぐ (to swim) > Oyogimasu
• Owaru 終わる (to end) > Owarimasu

Remember that just because a verb ends in -ru does not mean it functions as a ru-verb. Practice makes perfect when it comes to learning which verbs fall into which categories!

Applying Japanese Conjugation To The Potential Form

When you’re ready to try building the potential form, think about whether your verb is a ru-verb or an u-verb. If it’s a ru-verb, chop off the ru like you always would, then add rareru instead.

• Taberu > Taberareru (to eat > can eat)
• Neru > Nerareru (to sleep > can sleep)

This works if you want to conjugate into the formal -masu form (raremasu) or if you want to make it negative (rarenai or the more formal raremasen).

• Taberu > Taberarenai / taberaremasen (to eat > can’t eat)
• Neru > Nerarenai / neraremasen (to sleep > can’t sleep)

U-verbs do not behave too much differently. We’re going to change the “u” during conjugation the same way we would if we were just using -masu form; we’re just going to use a different vowel.

Let’s refresh how to change these verbs into –masu form:

• Utau > Utaimasu
• Oyogu > Oyogimasu
• Owaru > Owarimasu

Remember that you take that final u and change it to a different letter, in this case, to an “i” sound.

The same principle applies to the potential form as well — except you’re going to be using the “e” sound instead of the “i” sound. Replace that u with “eru” for the casual form, or just “e” if you’re using –masu.

• Utau > Utaeru / Utaemasu (to sing > can sing)
• Oyogu > Oyogeru / Oyogemasu (to swim > can swim)
• Owaru > Owareru / Owaremasu (to end > can end)

The same principle applies if you want to say you “can’t” instead, with an “e” sound before the negative endings -nai and -masen:

• Utau > Utaenai / Utaemasen (to sing > can’t sing)
• Oyogu > Oyogenai / Oyogemasen (to swim > can’t swim)
• Owaru > Owarenai / Owaremasen (to end > can’t end)

Exceptions To The Rule

Language wouldn’t be language without just a few exceptions to the general rules! The first one you should pay attention to is verbs that end with the syllable つ, “tsu.”

One example might be:

• Tatsu (to stand, 立つ)

When you want to turn tatsu into its potential form by changing the “u” sound to an “e” sound, you need to be particularly careful.

You might be tempted to say tatseru, but that doesn’t exist in Japanese. The actual corresponding syllable would be “te” instead.

Therefore, the correct potential form of tatsu is tateru. The same applies to all verbs ending in “-tsu” in their dictionary form.

Japanese also has two words that change completely when conjugated into the potential form.

They are:

• Suru する (to do)
  • Dekiru / Dekimasu (can do)
    • Dekinai / Dekimasen (can’t do)
• Kuru 来る (to come)
  • Korareru / Koraremasu (can come)
    • Korarenai / Koraremasen (can’t come))

If you use dekiru (or any of its other conjugations, like dekimasu) specifically, you’ll need to change the particle in your sentence from the normal wo that goes with suru to ga for dekiru.

Dekiru and the particle ga go together every time.

• Shigoto wo shimasu (I work)
  • 仕事をします
• Shigoto ga dekimasu (I can work)
  • 仕事ができます

When The Japanese Potential Form Doesn’t Mean “Can”

If you’re trying to put your newfound knowledge of the Japanese potential form into practice, you may be whipping up every sentence you can think of that includes can (like this one!).

However, it’s important to remember that there's a bit of nuance to the meaning of “can” or “cannot”. A few circumstances won’t allow you to use the potential form even if you’re creating a sentence about something that “can.”

For example, imagine that you’re talking to your family about how everyone at work is feeling under the weather.

It’s Bring Your Pet to Work Day, but you’re worried that your dog might catch the cold that everyone else has. Your mom says, “Oh, dogs don’t get human colds!” To which you respond, “Dogs can get sick too.”

Here we have an example of “can” that doesn’t quite fit the potential form. If you used the potential form here, you’d be saying, “Dogs have the ability to get sick if they really try to do so.”

Instead, when you mean “it is possible” for something to happen, there’s a different way to say that.

• Inu mo byouki ni naru koto mo aru (lit. There are also times when a dog gets sick.)
  • 犬も病気になることもある

This is different from using the potential form here, which would work like this:

• Inu wa byouki ni nareru (lit. A dog could have the ability to get sick [if he tried])
  • 犬は病気になれる

So if you are faced with situations where the “can” in your sentence means “it might happen sometimes” instead of posing a question of whether someone or something is literally capable of performing an action, you’ll need to avoid the potential form.

Another example might be if you say that your friend “can be annoying sometimes.” You don’t actually mean that you’re wondering whether she is able to be annoying (you probably already know).

You’re merely making a statement that every now and then, she gets a bit annoying.

• Mendokusai toki ga aru (lit. There are times she’s annoying)
  • めんどくさい時がある

So remember, when you want to use potential form, make sure you’re considering whether or not something is possible.

Japanese Potential Form FAQ

Japanese Potential Form: Don’t Give Up

Any time you learn a new grammatical construct, mastering it can seem impossible. But don’t give up – that's just the grammar villain talking!

The best way to learn is to immerse yourself in the language by listening to Japanese and speaking with Japanese native speakers and using your skills as much as you can. Or of course, looking at more examples by immersing yourself in story, as per the StoryLearning® method.

Don’t be afraid to be unsure – no one is going to get through learning a new language without making mistakes. Instead, learn from the areas that you’re unclear on so that you can figure out which things you need to spend some more time studying.

Before you know it, you’ll be using the Japanese potential form without even thinking about it. And because Japanese builds upon itself, you’ll be taking one step closer to making that next piece of Japanese grammar—whatever you choose—even simpler to learn than it would have been before.

Olly Richards

Creator of the StoryLearning® Method

Olly Richards is a renowned polyglot and language learning expert with over 15 years of experience teaching millions through his innovative StoryLearning® method. He is the creator of StoryLearning, one of the world's largest language learning blogs with 500,000+ monthly readers.

Olly has authored 30+ language learning books and courses, including the bestselling "Short Stories" series published by Teach Yourself.

When not developing new teaching methods, Richards practices what he preaches—he speaks 8 languages fluently and continues learning new ones through his own methodology.