「〜たとたん（に）」: the moment …
One thing has just happened and something else follows at once, and it is unexpected. The second half is usually beyond the speaker’s control: something falls, the weather changes, someone reacts, your body feels something. It is mostly used to tell what already happened.
verb ta form とたん（に）、something unexpected happens
In kanji, 「とたん」 is written 「途端」.
ドアを開けたとたん、猫が飛び出してきた。
The moment I opened the door, the cat shot out.
急に立ち上がったとたん、頭がくらっとした。
The moment I stood up too fast, I felt dizzy.
窓を開けたとたんに、冷たい風が吹き込んできた。
The moment I opened the window, cold air rushed in.
「いただきます」と言ったとたん、会社から電話がかかってきた。
The moment I said “itadakimasu”, the office called.
有名になったとたん、彼は態度が大きくなった。
As soon as he became famous, he became arrogant.
You can also use it for a change in someone else that you simply observed.
Watch out
Common mistakesThe second half can’t be your own plan, request or order. For “please call as soon as you get to the station”, say 「駅に着いたらすぐ電話してください」, not 「×駅に着いたとたん、電話してください」. The first half must be in the ta form: not 「×開けるとたん」.
Tip
「そのとたん」 and 「とたんに」You can also finish the first event and then continue with 「そのとたん」: 「ボタンを押した。そのとたん、画面が真っ暗になった」. On its own, 「とたんに」 is an adverb meaning “instantly, suddenly”.
「〜次第」: as soon as … (formal)
「次第」 follows the masu stem and means “as soon as …, (someone) will …”. The second half is something the speaker will do or a request to someone. It is formal and common in notices, business emails, phone calls and announcements at stations and shops.
masu stem 次第、what you will do / a request
Action nouns used with 「〜する」 can take it directly: 「到着次第」, 「確認次第」.
| Original form | How to attach it | Example |
|---|---|---|
| わかる | わかり次第 | 原因がわかり次第、ご報告します。 |
| 決まる | 決まり次第 | 日程が決まり次第、お知らせします。 |
| できる | でき次第 | 準備ができ次第、出発します。 |
| 到着する | 到着次第 | 到着次第、お電話ください。 |
担当者が戻り次第、こちらからお電話します。
We’ll call you back as soon as the person in charge returns.
A very common reply on the phone.
商品が入荷次第、メールでご連絡いたします。
We’ll email you as soon as the item comes into stock.
雨がやみ次第、試合を再開します。
The match will resume as soon as the rain stops.
The first half can be beyond anyone’s control, but the second half must be something done on purpose.
会議が終わり次第、そちらに向かいます。
I’ll come over as soon as the meeting ends.
Watch out
Common mistakesThe second half of 「次第」 can’t be in the past: for “I called as soon as I arrived”, say 「着いてすぐ電話しました」, not 「×着き次第、電話しました」. It can’t be something that happens naturally either: not 「×春になり次第、桜が咲きます」.
Tip
Don’t confuse it with noun + 「次第で」In 「天気次第で、予定を変えます」, 「次第で」 means “depending on …”. It follows a noun directly and has nothing to do with this lesson’s “as soon as”. For now, just learn to recognise it.
「〜たらすぐ」 「〜てすぐ」: the everyday “as soon as”
In everyday speech the most common way is 「たら」 from N4 lesson 4 plus 「すぐ」, or the te form plus 「すぐ」. They only say one thing follows another, with no surprise and no formality, and the second half can be anything: your plans, requests or past events.
家に着いたらすぐ、連絡してね。
Let me know as soon as you get home.
昨日は疲れていたので、晩ご飯を食べてすぐ寝ました。
I was tired yesterday, so I went to bed right after dinner.
授業が終わったら、すぐアルバイトに行かなきゃ。
I have to go straight to my part-time job after class.
| Comparison | 「〜たらすぐ」 「〜てすぐ」 | 「〜次第」 | 「〜たとたん」 |
|---|---|---|---|
| Tone | neutral, spoken or written | formal: notices, business | narrative, with surprise |
| Second half is your plan or request | Yes | Yes, and only this | No |
| Talking about the past | Yes (「てすぐ」 is more common) | No | Yes, mostly the past |
| Second half is unexpected | Yes | No | That’s exactly its meaning |
How to choose: first ask whether the second half is something you will do. If it is, use 「次第」 when formal and 「たらすぐ」 otherwise; if it is something you didn’t expect, use 「たとたん」.
「〜ついでに」: while you’re at it
「ついでに」 means: you were going to do A anyway, so you take the chance to do B as well. The first half is the main thing; the second is the extra.
dictionary form / ta form / noun + の ついでに、what you do on the side
郵便局へ行くついでに、この手紙も出してきてくれる？
If you’re going to the post office, could you post this letter for me too?
大阪へ出張したついでに、昔の友だちに会ってきた。
While I was in Osaka on business, I also saw an old friend.
買い物のついでに、銀行でお金を下ろしてきた。
While I was out shopping, I also took some money out at the bank.
部屋を掃除したついでに、窓も拭いておいた。
While cleaning the room, I wiped the windows too.
コーヒーを入れるなら、ついでにわたしの分もお願い。
If you’re making coffee, could you make me one too?
「ついでに」 can also be used on its own as an adverb.
Tip
Dictionary form or ta formFor something done on the way or before, use the dictionary form: 「郵便局へ行くついでに」. For something done once you are there or have finished, use the ta form: 「大阪へ行ったついでに」.
Watch out
Common mistakesKeep the main thing and the extra the right way round. If the trip to Osaka was mainly for work, say 「出張のついでに友だちに会った」; 「友だちに会うついでに出張した」 would mean seeing your friend was the main purpose.
Compare
ついでに means “while you’re at it” or “while I’m there”, not “by the way”. To change the subject with “by the way”, say 「ところで」.
Compared with similar expressions
| Expression | Tone and setting | Second half | Example |
|---|---|---|---|
| 「〜たとたん」 | narrative, unexpected | beyond your control, mostly past | 座ったとたん、いすが壊れた。 |
| 「〜次第」 | formal: notices, business | what you will do or a request; never the past | 決まり次第、ご連絡します。 |
| 「〜たらすぐ」 | spoken, neutral | anything | 着いたらすぐ電話してね。 |
| 「〜てすぐ」 | neutral, often for things that already happened | your own actions are fine | 帰ってすぐ寝た。 |
| 「〜ついでに」 | using one chance to do something extra | the extra thing | 買い物のついでに銀行に寄った。 |
| 「〜ながら」 | two actions at the same time | the main action | 歩きながら電話する。 |
Where they can’t be swapped:
- If the second half is a request or plan: not 「たとたん」; use 「次第」 or 「たらすぐ」.
- For something you did in the past: not 「次第」; use 「てすぐ」 or 「たらすぐ」.
- To show surprise, use 「たとたん」; 「たらすぐ」 and 「てすぐ」 only give the order.
- 「ながら」 means doing two things at once; 「ついでに」 means doing an extra thing on the occasion of another, not necessarily at the same time.
- 山田
高橋さん、さっきの電話、何でしたか。
Takahashi, what was that call just now?
- 高橋
取引先から。注文した部品がまだ届かないって。工場に確認して、わかり次第ご連絡しますって答えておいた。
A client. The parts they ordered still haven’t arrived. I said I’d check with the factory and get back to them as soon as I knew.
- 山田
大変ですね。あ、今から郵便局に行くんですけど、ついでに何か出してきましょうか。
That sounds stressful. Oh, I’m going to the post office now. Want me to post anything for you while I’m there?
- 高橋
助かる。じゃあ、この封筒をお願い。そういえば、昨日の飲み会はどうだった？
That would help. Could you take this envelope? By the way, how was the drinks party yesterday?
- 山田
それが、店に入ったとたん、部長と目が合っちゃって。
Don’t ask. The moment I walked into the restaurant, I caught the manager’s eye.
- 高橋
えっ、それは気まずいね。
Oh, that’s awkward.
- 山田
でも、結局部長がごちそうしてくれました。
But in the end the manager paid for everyone.
- 高橋
よかったじゃない。
Well, that’s good, isn’t it?
- 山田
郵便局から戻ったらすぐ、工場の件、手伝いますね。
As soon as I’m back from the post office, I’ll help you with the factory issue.
Takahashi tells the client formally that he’ll get in touch as soon as he knows: 「わかり次第」. Yamada posts the letter while going to the post office anyway: 「ついでに」. Bumping into the manager the moment he walked in was unexpected: 「入ったとたん」. Helping as soon as he’s back is his own plan: 「戻ったらすぐ」.