A2
たら — if, and when
How the Japanese たら conditional is formed and used, why it covers both “if” and “when”, and how it differs from と.
Take the plain past and add ら. That is the whole formation, and it works on verbs, adjectives and nouns alike.
| 行った → 行ったら | if / when I go |
| 食べた → 食べたら | if / when I eat |
| 寒かった → 寒かったら | if it’s cold |
| 学生だった → 学生だったら | if I were a student |
雨が降ったら、行きません。
Ame ga futtara, ikimasen.
If it rains, I won’t go.
駅に着いたら、電話します。
Eki ni tsuitara, denwa shimasu.
I’ll call you when I get to the station.
If and when are the same word
The second example is not a condition — you will certainly arrive. たら covers both, and which one is meant comes from whether the event is in doubt.
It is not a past tense
The た is borrowed formation, nothing more. 行ったら is if I go, and the sentence can be entirely about the future.
雨が降ったら、行きませんでした。
雨が降ったら、行きません。
The たら clause sets a condition, so the result belongs in the present or future. A past result would need a different structure entirely.
Against と
と states an automatic consequence — one thing always follows the other. It cannot be used when the second clause is a request, an invitation or an intention, which is most of the time.
春になると、桜が咲きます。
Haru ni naru to, sakura ga sakimasu.
When spring comes, the cherry trees blossom.
That is a law of the world, not a plan. Swap in something you have decided and と stops working, while たら keeps going: 春になったら、日本に行きます.
Discovering something
With a past main clause, たら stops being conditional and marks what you found on doing something.
家に帰ったら、誰もいませんでした。
Ie ni kaettara, dare mo imasen deshita.
When I got home, there was nobody there.