Grammar Comparison
The four conditionals: と・ば・たら・なら
Four ways to say “if / when” — and when to use each
Japanese has four conditional forms and they are not interchangeable. The quickest way to choose: と for automatic results, ば for general conditions and advice, たら for “after/when X then do Y” (the most flexible — it allows requests and commands), and なら for reacting to a topic someone just raised.
〜と
to
Automatic, inevitable result
“Whenever A happens, B always happens.” Used for natural laws, machines, directions, habits. The B-clause CANNOT be a request, command, invitation, or your own intention.
春になると、桜が咲きます。
はるになると、さくらがさきます。 · haru ni naru to, sakura ga sakimasu.
When spring comes, the cherry blossoms bloom.
〜ば
ba
General / hypothetical condition
Emphasises the condition itself: “if A (were the case), then B.” Common in advice, proverbs, and what-if talk. Restricted before requests/commands when A is an action verb.
安ければ、買います。
やすければ、かいます。 · yasukereba, kaimasu.
If it’s cheap, I’ll buy it.
〜たら
tara
After / when A, then B (most flexible)
The all-purpose conditional. Works for one-time future events and sequences, and — unlike と・ば — it freely allows requests, commands, suggestions, and intentions in the B-clause.
駅に着いたら、電話してください。
えきについたら、でんわしてください。 · eki ni tsuitara, denwa shite kudasai.
When you arrive at the station, please call me.
〜なら
nara
If it’s the case that A / speaking of A
Contextual: you react to a topic the other person just raised or a supposition. Often topic-like (“As for going to Japan…”). Not for time sequences.
日本に行くなら、京都がいいですよ。
にほんにいくなら、きょうとがいいですよ。 · nihon ni iku nara, kyouto ga ii desu yo.
If you’re going to Japan, Kyoto is good.
Quick decision guide
An automatic, always-true result
→ 〜と
General advice, a proverb, or a what-if
→ 〜ば
“After / when X happens, then do Y”
→ 〜たら
A request or command in the result
→ 〜たら
Reacting to a topic someone just raised
→ 〜なら
Common mistakes
家に帰ると、手を洗ってください。
家に帰ったら、手を洗ってください。
〜と cannot be followed by a request or command. For “when you get home, please wash your hands,” use 〜たら.
京都に着くなら、写真を撮ります。
京都に着いたら、写真を撮ります。
For a real future event in sequence (“after I arrive”), use 〜たら. 〜なら sets up a supposition or topic, not a time sequence.