Japanese refresher · 5 minutes · 0004
〜たら vs. 〜なら
Both can translate as “if.” The useful question is: am I waiting for an event, or taking a premise as the basis for advice?
The mental model
たら: “Once/if A happens, B.”
なら:
“Given A / if that’s the case, B.”
京都に着いたら、連絡して。
Contact me once you arrive in Kyoto.
京都に行くなら、先にホテルを予約したほうがいいよ。
If you’re going to Kyoto, you should book a hotel first.
The booking can happen before the trip. なら does not make the trip a completed trigger. This distinction is explained in Tokyo University of Foreign Studies’ conditionals module.
Listen for the premise
A: 明日、車で行こうと思ってる。
B:
車で行くなら、早めに出たほうがいいよ。
A: わかった。着いたら、メッセージ送るね。
B responds to A’s plan; A then names the arrival that will trigger the message. なら can also introduce your own hypothetical premise—it does not require someone else to have said it first.
時間がないなら、今日はやめておこう。
If we don’t have time, let’s leave it for today.
The た-form does not mean “past” here
明日、雨が降ったら、家にいる。
If it rains tomorrow, I’ll stay home.
たら can mark an uncertain condition, not only “after.” It also introduces a discovery:
家に帰ったら、窓が開いていた。
When I got home, I found the window open.
The window need not have opened after your arrival; arrival gave you access to the discovery. The Japan Foundation’s たら notes cover hypothetical, temporal, and discovery uses. Recall lesson 0003: 開いていた describes the resulting state at that past viewpoint.
Build the forms as packages
| Base | たら | なら |
|---|---|---|
| 行く | 行ったら | 行くなら |
| 行かない | 行かなかったら | 行かないなら |
| 安い | 安かったら | 安いなら |
| 暇だ／雨だ | 暇だったら／雨だったら | 暇なら／雨なら |
These are core forms, not the entire conditional system. With states, both choices can fit: 安かったら買う and 安いなら買う can both be natural, with different framing.
A preparation trap
You want someone to buy a ticket before boarding:
△ 電車に乗ったら、先に切符を買って。
○
電車に乗るなら、先に切符を買って。
The first makes boarding the trigger, clashing with “buy first” in this situation. The second means “if you’re taking the train, buy a ticket first.” Neither ending is simply a universal replacement for English “if.”
45-second retrieval drill
Choose the form matching the stated intention. Say the whole sentence before clicking.
1. 空港に＿＿、メッセージを送って。
Send it after you arrive—not just if a trip is planned.
着いたら: arrival first, message afterward.
2. 海外に＿＿、出発前にパスポートの期限を確認して。
Respond to a proposed trip with preparation advice.
行くなら: the plan is the premise; the check happens before departure.
3. In your own words, contrast these two:
仕事が終わったら、電話する。
仕事が終わっているなら、電話してもいい？
First: finishing work triggers my call. Second: if your work is already finished, may I call? 終わっている presents a resulting state as the premise.
Mental hook: event reached, or premise accepted? Tomorrow, retrieve one preparation sentence and one after-arrival sentence without looking.