LESSON NOTES · レッスンノート

N4Talking to real people · Sep 20, 2026

だいたい: "roughly", "mostly", and the one that means "in the first place

だいたい does three separate jobs: it makes a number approximate, it says something is true most of the time, and — dropped at the front of a sentence — it means "in the first place", which is how a Japanese argument announces itself.

The first two are in every textbook. The third is not in any of them, and it is the one you will hear in real conversation and in anime, usually right before someone loses their temper. All three are the same word, and the position in the sentence tells you which one is running.

The basics

だいたい with a number

Put it before the amount, and the amount becomes approximate.

だいたい三十さんじゅう分わかかります。 — It takes roughly thirty minutes. (polite) だいたい千円せんえんぐらいです。 — It's about a thousand yen. (neutral — だいたい and ぐらい together is normal)

Note the position: だいたい goes before the number, unlike くらい which goes after. Using both at once is not redundant to Japanese ears — it is the ordinary way to sound relaxed about a figure. The くらい half of that sentence is covered in くらい or ぐらい.

だいたい with an action

Here it stops being about numbers and becomes about coverage: most of it, in the main, by and large.

宿題しゅくだいはだいたい終おわりました。 — I've mostly finished the homework. (polite) 話はなしはだいたい分わかりました。 — I understood the gist of it. (polite — extremely common)

だいたい分わかりました is one of the most useful sentences a learner can own. It is honest — it says you got the shape, not every word — and it keeps a conversation moving instead of stopping it for a full repair.

だいたい as "usually"

With a habit, it slides into "generally, as a rule".

朝あさはだいたいパンを食たべます。 — I generally have bread in the morning. (polite)

This is the use that overlaps with たいてい, and for most sentences either word works.

Beyond the basics

だいたい at the start of a sentence

Front-load it and the meaning changes completely: "in the first place", "to begin with". It reopens the whole question instead of qualifying an amount.

だいたい、お前まえが悪わるいんだろ。 — In the first place, this is your fault, isn't it. (casual, confrontational) だいたい、そんな話はなしは聞きいていない。 — For a start, nobody told me about this. (casual, annoyed)

It signals that the speaker is done with the current point and is going back to the beginning of the argument. In anime it is frequently the line that turns a disagreement into a fight, and the tone attached to it is almost never neutral. そもそも does the same job in more formal register.

だいたい vs たいてい vs ほとんど

Three words English flattens into "mostly", and they measure different things.

Word Measures Example
だいたい Amount or extent — how much of it 宿題しゅくだいはだいたい終おわった
たいてい Frequency — how often たいてい家いえにいます
ほとんど A near-total proportion, often with a negative ほとんど分わからない

たいてい家いえにいます。 — I'm usually at home. (polite — frequency) ほとんど分わかりません。 — I hardly understand any of it. (polite — near zero)

The trap is ほとんど, which with a negative verb flips to "hardly any". ほとんど分わからない is much weaker understanding than だいたい分わかった, and confusing them is the difference between "I got the gist" and "I got almost nothing".

だいたい vs 約やく vs およそ

約やく and およそ are the written, formal versions of the numerical use.

約やく三十さんじゅう分わかかります。 — It takes approximately thirty minutes. (formal — signage, announcements)

約やく belongs on signs and in documents; およそ is similar and slightly more literary. Neither sounds natural in casual speech, where だいたい is the word people actually use.

大体だいたい and 大概たいがい

Both are written with kanji you will meet: 大体だいたい is だいたい, and 大概たいがい (たいがい) is a near-synonym of たいてい meaning "generally, in most cases". 大概たいがい also has a scolding idiom attached — いい加減かげんにしろ's cousin 大概たいがいにしろ, "that's enough of that" — which is worth recognising even though you will rarely say it.

Common mistakes

  • Putting だいたい after the number. It goes before: だいたい三十さんじゅう分ふん, not 三十さんじゅう分ふんだいたい. くらい is the one that goes after.
  • Using だいたい for frequency when you mean たいてい. Both are possible with habits, but for "how often" specifically, たいてい is the precise word.
  • Reading ほとんど分わからない as "I mostly understand". With a negative, ほとんど means "hardly any" — the opposite of what it looks like.
  • Using 約やく in conversation. It is correct but stiff. In speech it sounds like reading from a notice.
  • Missing sentence-initial だいたい. If だいたい opens the sentence with no number in sight, the speaker has just reopened the argument.

The three positions

Position Meaning Example
Before a number Roughly, about だいたい三十さんじゅう分ふん
Before a verb or after a topic Mostly, the gist of だいたい分わかりました
At the start of a sentence In the first place, to begin with だいたい、お前まえが悪わるい

FAQ

Can I use だいたい and くらい in the same sentence? Yes, and it is completely normal: だいたい三十さんじゅう分わくらい. It sounds relaxed rather than redundant.

Is だいたい casual? It is neutral. It works in polite speech — だいたい分わかりました is something you can say to a teacher or a client without any problem.

How do I say "I mostly understood" without sounding like I understood everything? だいたい分わかりました is exactly that. It claims the gist and nothing more, which is why it is safer than 分わかりました alone when you are not sure.

What is the difference between だいたい and 大体だいたい? None — 大体だいたい is just the kanji spelling of the same word. You will see both in writing.

Does だいたい ever sound rude? The sentence-initial one can. だいたい、お前まえが… is confrontational by design. The other two uses are neutral.

What is そもそも? The more formal equivalent of sentence-initial だいたい: "fundamentally, to begin with". Same move, different register.

Practice

Build each answer before opening it. Questions 4 and 5 are a pair — the same word doing two different jobs.

1. Say "it takes roughly thirty minutes."

Show answer

だいたい三十さんじゅう分わかかります — だいたい goes before the number.

2. Something is wrong here: 三十さんじゅう分ふんだいたいかかります。

Show answer

だいたい三十さんじゅう分わかかります — the one that goes after the number is くらい, not だいたい.

3. Tell someone you got the gist of what they said.

Show answer

話はなしはだいたい分わかりました — honest, polite, and it keeps the conversation moving.

4. Translate: 宿題しゅくだいはだいたい終おわりました。

Show answer

I've mostly finished the homework — extent. This is the pair to question 5.

5. Translate: だいたい、そんな話はなしは聞きいていない。

Show answer

For a start, nobody told me about this — sentence-initial だいたい reopens the argument. This is the pair to question 4.

6. Say "I'm usually at home" — about frequency.

Show answer

たいてい家いえにいます — for how often, たいてい is the precise word.

7. Translate: ほとんど分わかりません。

Show answer

I hardly understand any of it — with a negative, ほとんど means "almost none", not "mostly".

8. Which is stronger understanding: だいたい分わかった or ほとんど分わからない?

Show answer

だいたい分わかった — it means you got the gist. ほとんど分わからない is close to nothing.

9. You are writing a sign about a thirty-minute wait. Which word?

Show answer

約やく — 約やく三十さんじゅう分ふん. 約やく belongs on signage; in speech it sounds like reading aloud from a notice.

10. A character opens with だいたい、お前まえが…. What is about to happen?

Show answer

An argument — sentence-initial だいたい abandons the current point and goes back to the beginning, usually with heat behind it.

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.

大体	だいたい — roughly; mostly; in the first place
大抵	たいてい — usually, generally
ほとんど	ほとんど — almost all; (with negative) hardly any
約	やく — approximately (written)
およそ	およそ — roughly (written, literary)
宿題	しゅくだい — homework
終わる	おわる — to finish
分かる	わかる — to understand
話	はなし — story, what was said
朝	あさ — morning
悪い	わるい — bad, at fault
聞く	きく — to hear, to ask
家	いえ — house, home
時間	じかん — time, hour
かかる	かかる — to take (time, money)
程度	ていど — degree, extent

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. だいたい分わかりました is the sentence I most want beginners to own — it is the honest answer, and it keeps the lesson moving instead of stopping it dead.

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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

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