LESSON NOTES · レッスンノート

N4Grammar, one piece at a time · Sep 24, 2026

How do you say "enough" in Japanese? 十分じゅうぶん, 足たりる and もういい

Japanese splits "enough" into three different jobs: 十分じゅうぶん (じゅうぶん) says something is sufficient, 足たりる (たりる) says the amount covers what you need, and もういい says "that's enough, stop." お金きんは十分じゅうぶんある, お金きんが足たりる and もういい! all translate as "enough," and none of them can stand in for the others.

The mix-ups are predictable once you see the split. Learners use 十分じゅうぶん to stop someone talking, or 足たりる to praise something as "good enough," and both come out slightly strange.

The basics

What does 十分じゅうぶん mean?

十分じゅうぶん (じゅうぶん) is "sufficient, plenty." It describes a quantity or a quality as meeting the need, and it works as a na-adjective (十分じゅうぶんな時間じかん, plenty of time) and an adverb (十分じゅうぶんわかる, I understand it well enough).

時間じかんは十分じゅうぶんあります。 — We have plenty of time. (sufficient) これで十分じゅうぶんです。 — This is plenty. / This will do. (polite, accepting what you're given) 一人ひとりで十分じゅうぶんできる。 — I can easily do it on my own. (adverb: well enough)

The kanji are "ten parts" — ten out of ten. You will also see 充分じゅうぶん, with the same reading and meaning. Both are correct; 十分じゅうぶん is the one newspapers and textbooks use.

How is 十分じゅうぶん read — じゅうぶん or じっぷん?

It depends on meaning. As "enough" it is always じゅうぶん. As "ten minutes" it is じっぷん or じゅっぷん. The characters are identical, so context does all the work.

駅えきまで十分じゅうぶん(じっぷん)かかる。 — It takes ten minutes to the station. (time) 十分じゅうぶん(じゅうぶん)間に合まにあう。 — We'll easily make it. (enough)

A sentence like 十分じゅうぶんで着つく is genuinely ambiguous in writing — "arrive in ten minutes" — and a listener only knows it is minutes because of じっぷん. When you speak, the reading removes the doubt.

What about 足たりる?

足たりる is a verb: "to be enough," "to suffice." It is about amount — is there enough of the thing to cover the need? Its negative, 足たりない, is used even more often, for anything that falls short.

千円せんえんで足たりる? — Is a thousand yen enough? (asking about amount) 椅子いすが一ひとつ足たりない。 — We're one chair short. (shortfall) 寝不足ねぶそくで、集中力しゅうちゅうりょくが足たりない。 — I didn't sleep enough, so I can't concentrate. (lacking)

Note the particle: the thing that is (or is not) enough takes が. お金きんが足たりない, not お金きんを足たりない.

Side by side

Word Type Question it answers Example
十分じゅうぶん na-adjective / adverb Is it sufficient? 時間じかんは十分じゅうぶんある
足たりる / 足たりない verb Does the amount cover it? お金きんが足たりない
もういい phrase Should we stop? もういい、やめよう
いい加減かげんにして phrase Will you stop already? いい加減かげんにして!
結構けっこうです phrase No more, thank you もう結構けっこうです

Beyond the basics

How do you say "that's enough!"?

This is where anime comes in, and where 十分じゅうぶん is the wrong choice. To stop something, Japanese uses いい ("good, fine") in the sense of "we're done."

もういい! — Enough! / Forget it! (frustrated, sharp) もういいよ。 — It's fine, you can stop now. (soft, often kind) いい加減かげんにして! — Cut it out! / That's enough! (exasperated)

The same もういい can be warm or cold depending on the tone and the よ. Said gently to someone apologising over and over, もういいよ means "it's okay, you don't need to keep saying sorry." Shouted and followed by a door slamming, it means the conversation is over. いい加減かげんにしろ is the rough, mostly male version you hear in shouting matches on screen.

How do you politely say "that's enough, thank you"?

At a table, when someone offers more food or another drink, the polite refusal is 結構けっこうです or もう十分じゅうぶんです.

もう十分じゅうぶんいただきました。 — I've had plenty, thank you. (very polite) いえ、もう結構けっこうです。 — No, I'm fine, thank you. (polite refusal)

結構けっこうです is tricky because it can also mean "that's fine" as a yes. The もう and the tone decide it: もう結構けっこうです is almost always "no more." When turning down offers in general, a small ありがとうございます in front keeps it warm. Other soft refusals are in how to say no in Japanese, and the words around the meal itself are in いただきます and ごちそうさま.

Why does 十分じゅうぶん sometimes sound cold?

Because "sufficient" can imply "not more than sufficient." If a friend shows you a drawing they worked hard on and you say 十分じゅうぶんだよ, it can land as "it's adequate." For praise, use a real compliment instead: すごい, いいね, 上手じょうず.

The same thing happens in English with "it'll do." 十分じゅうぶん is a verdict about need, not a compliment.

What does 〜で十分じゅうぶん mean?

〜で十分じゅうぶん is "just 〜 is enough" — a humble way to say you don't need more.

水みずで十分じゅうぶんです。 — Water is fine for me. (don't go to any trouble) コンビニのおにぎりで十分じゅうぶん。 — A convenience-store rice ball is all I need. (casual)

It pairs naturally with offers: someone asks what you would like, and 〜で十分じゅうぶんです says you are happy with the simple option. For the rhythm of too much and too little, 〜すぎる is the natural next step — 食たべすぎ is what happens when 十分じゅうぶん is ignored.

Common mistakes

  • Using 十分じゅうぶん to stop someone. 十分じゅうぶん! as "enough, stop!" sounds odd. Use もういい or やめて.
  • Using を with 足たりる. お金きんを足たりない is wrong. The amount takes が: お金きんが足たりない.
  • Reading 十分じゅうぶん as じっぷん when you mean "enough." じっぷん is ten minutes. "Enough" is always じゅうぶん.
  • Praising with 十分じゅうぶん. 十分じゅうぶん上手じょうず can sound like "skilled enough, barely." For a compliment, just say 上手じょうず.
  • Saying 足たりません for "no thanks." At a table, 足たりません means "there isn't enough" — the opposite of what you want. Say もう十分じゅうぶんです or 結構けっこうです.
  • Forgetting that もういい depends on tone. The same words can comfort or end a conversation. Add よ and soften your voice when you mean kindness.

Practice

Answers are hidden — build yours first, then open. Questions 1 and 2 are a pair: the same idea from two sides.

1. Say "We have plenty of time," politely.

Show answer

時間じかんは十分じゅうぶんあります — sufficiency, so 十分じゅうぶん. は contrasts time with other things you may be short of.

2. Say "We don't have enough time."

Show answer

時間じかんが足たりない — a shortfall, so 足たりない. 十分じゅうぶんじゃない is possible but less common in speech.

3. Ask a friend: "Is two thousand yen enough?"

Show answer

二千にせん円えんで足たりる? — a question about amount, so 足たりる. で marks the amount you are testing.

4. Someone keeps apologising. Tell them kindly it's fine and they can stop.

Show answer

もういいよ — soft もういい with よ. Said gently, it releases the other person.

5. At dinner, the host offers more food. Refuse politely.

Show answer

もう十分じゅうぶんいただきました (or いえ、もう結構けっこうです) — polite refusal. 足たりません would say the opposite.

6. Read this aloud correctly: 十分じゅうぶんで駅えきに着つきます (it means ten minutes).

Show answer

じっぷん(じゅっぷん)で駅えきに着つきます — time reading. じゅうぶん would change it to "enough."

7. Tell someone who offered you a drink that water is fine.

Show answer

水みずで十分じゅうぶんです — 〜で十分じゅうぶん is "just this is enough," a humble way to decline anything fancier.

8. Fix: 財布さいふにお金きんを足たりない。

Show answer

財布さいふにお金きんが足たりない — 足たりる takes が for the thing that falls short.

9. Your roommate has played the same song twenty times. Snap at them: "Cut it out!"

Show answer

いい加減かげんにして! — exasperated "that's enough." 十分じゅうぶん would never work here.

FAQ

Is 十分じゅうぶん the same as 充分じゅうぶん? Same reading, same meaning. 十分じゅうぶん is the standard spelling; 充分じゅうぶん is common in novels and ads and suggests "full" rather than "ten out of ten."

Is 十分じゅうぶん an adjective or an adverb? Both. 十分じゅうぶんな時間じかん (adjective, with な) and 十分じゅうぶんわかる (adverb, no particle) are both normal.

What is 不十分ふじゅうぶん? "Insufficient." It is formal — reports, reviews, feedback. In conversation 足たりない is more natural.

How do you say "I've had enough of this"? もううんざり or もう嫌いやだ. These express being fed up, which is emotional rather than a statement about amount.

Can I say じゅうぶん in casual speech? Yes. 十分じゅうぶんだよ and それで十分じゅうぶん are everyday casual phrases.

Why does anime use もういい so much? Because it compresses a whole argument into two words. It can mean "forget it," "I give up on you," or "it's okay now," and the voice acting tells you which.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

十分	じゅうぶん — enough, sufficient, plenty
足りる	たりる — to be enough, to suffice
足りない	たりない — not enough, short of
結構	けっこう — fine; (もう結構です) no more, thank you
いい加減	いいかげん — (いい加減にして) cut it out
時間	じかん — time
間に合う	まにあう — to make it in time
椅子	いす — chair
寝不足	ねぶそく — lack of sleep
集中力	しゅうちゅうりょく — concentration
上手	じょうず — skilful, good at
財布	さいふ — wallet
不十分	ふじゅうぶん — insufficient
充分	じゅうぶん — enough (alternative spelling)
駅	えき — station
水	みず — water
嫌	いや — unpleasant, not wanting

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime. 十分じゅうぶん comes up in lessons when a student hears じゅうぶん and thinks I said 自分じぶん — which is a good moment to sort out the whole "enough" family at once.

Book a trial lesson · $13

Sources: the author's own lessons and standard reference grammars.

More drills like the ones above, plus a timed JLPT-style mock test: Practice · N4

Want to try this in a real conversation?

30-minute trial lesson, $13. Times shown in your own timezone.

Book a trial lesson · $13