〜次第 (しだい): 'As Soon As' / 'Depending On'
What it means
次第 (しだい) is one word doing three related jobs, all built on the idea of "what follows from / what something hinges on."
- ます-stem + 次第 = as soon as something happens (a future event).
- noun + 次第だ = the outcome depends on that noun.
- noun + 次第で(は) = depending on that noun, things vary.
It belongs to formal register — written notices, business email, and announcements. Sense 1 in particular is the standard polite way to promise "I'll do X the moment Y happens."
資料が届き次第、お送りします。
しりょうが とどきしだい、おおくりします。
I'll send the materials as soon as they arrive.
ます-stem 届き + 次第 = as soon as. Result is future.
合格できるかどうかは、あなた次第です。
ごうかく できるかどうかは、あなたしだいです。
Whether you can pass depends on you.
noun + 次第だ = it's up to / depends on.
モチの気分次第で、行く店が変わる。
モチの きぶんしだいで、いく みせが かわる。
Which restaurant we go to changes depending on Mochi's mood.
noun + 次第で = depending on.
How to form it
| Sense | Pattern | Example |
|---|---|---|
| As soon as | Verb ます-stem + 次第 | 終わり次第（おわりしだい） |
| Depends on | Noun + 次第だ／です | 努力次第だ（どりょくしだいだ） |
| Depending on | Noun + 次第で(は) | 天気次第で（てんきしだいで） |
Note for sense 1: you attach 次第 to the verb stem (the part before ます), not the dictionary form — 着き次第 (not 着く次第), 決まり次第 (not 決まる次第).
Sense 1: "as soon as" (future only)
This is the one that shows up constantly in business Japanese. The key rule: because 次第 here means "the instant Y happens, X will follow," the main clause has to be future — a plan, a promise, or a request. You cannot use it to narrate something that already happened.
ヤッタンが駅に着き次第、電話します。
ヤッタンが えきに つきしだい、でんわします。
I'll call as soon as Yattan reaches the station.
日程が決まり次第、改めてご案内いたします。
にっていが きまりしだい、あらためて ごあんない いたします。
As soon as the schedule is set, I'll let you know again.
改めて + humble いたします — classic business email tone.
To talk about a past "as soon as," reach for 〜たら or 〜とすぐに instead: 着いたらすぐ電話した ("I called as soon as I arrived").
Sense 2 & 3: "depends on" / "depending on"
With a noun, 次第 says the result is governed by that noun. Use 次第だ／です when it sits at the end as the predicate, and 次第で(は) when the clause continues to describe what varies.
テストの結果は、毎日の勉強次第だ。
テストの けっかは、まいにちの べんきょうしだいだ。
The test result depends on your daily studying.
次第だ closes the sentence = it depends on.
先生の説明次第で、宿題の量が変わります。
せんせいの せつめいしだいで、しゅくだいの りょうが かわります。
The amount of homework changes depending on the teacher's explanation.
天気次第では、ピクニックは中止です。
てんきしだいでは、ピクニックは ちゅうしです。
Depending on the weather, the picnic may be canceled.
次第では adds 'in some cases' — a possible outcome.
The は in 次第では highlights one possible branch ("in some cases, depending on…"), so it pairs naturally with a result that might happen. This noun-based 次第 overlaps with 〜によって ("depending on / according to"); 次第 feels a touch more formal and is especially common with "it's up to you" nuances.
Common mistakes
- Using sense 1 with a past main clause. 次第 ("as soon as") promises a future action: 着き次第連絡します (✓). For "I called as soon as I arrived," use 着いたらすぐ電話した (✗ 着き次第電話した).
- Attaching to the dictionary form. Sense 1 needs the ます-stem: 終わり次第 (✓), not 終わる次第 (✗).
- Mixing the two senses. ます-stem + 次第 = "as soon as"; noun + 次第 = "depends on." 努力次第 is "depends on effort," never "as soon as you effort."
- Forgetting で for sense 3. To say "depending on X, Y varies," you need 次第で: 天気次第で変わる (✓), not 天気次第変わる (✗).
Quick recap
- Verb ます-stem + 次第 = as soon as; main clause must be future (formal, business).
- Noun + 次第だ = it depends on (predicate at sentence end).
- Noun + 次第で(は) = depending on, things vary; では flags a possible outcome.
- For a past "as soon as," use 〜たら / 〜とすぐに, not 次第.
Your turn
Pick the right use of 次第 / 次第だ / 次第で.
Start the 5-question drill →Frequently asked questions
Can I use 〜次第 about something that already happened?
No. The ます-stem + 次第 ('as soon as') sense points to a future action, so the main clause must be a plan, promise, or request: 届き次第送ります. For a past event use 〜たら or 〜とすぐに: 届いたらすぐ送った.
Does 次第 attach to the dictionary form or the ます-stem?
For the 'as soon as' meaning, use the ます-stem: 終わり次第, 決まり次第, 着き次第 — never the dictionary form 終わる次第.
What's the difference between 次第だ and 次第で?
次第だ ends the sentence ('it depends on X'): 結果は努力次第だ. 次第で continues the clause to say what varies ('depending on X, Y changes'): 天気次第で予定が変わる.
How is noun + 次第で different from 〜によって?
They overlap for 'depending on.' 次第 leans more formal and is the go-to for 'it's up to you' (あなた次第), while によって is broader and also covers 'by means of' and 'according to.'