Examples
Meaning
Both 〜と and 〜たら can express if or when, but they do not focus on the same thing. 〜と is used when B happens naturally or automatically after A. 〜たら is used when A is completed and then B happens, is planned, or is requested.
Formation
For 〜と, use a plain non-past form before と, such as 押すと. For 〜たら, use the past plain form plus ら, such as 押したら.
Usage
Use 〜と for machines, directions, general truths, habits, and automatic results. Use 〜たら for one-time future events, requests, plans, choices, and discoveries.
Nuance
〜と sounds objective and predictable. 〜たら sounds more flexible and conversational. When you want to tell someone what to do after something happens, 〜たら is usually safer and more natural.
Comparison
このボタンを押すと、音が出ます explains an automatic result. 準備ができたら、教えてください gives a request after a condition is met. Replacing the second sentence with 〜と would sound unnatural because the second clause is a request.
Common Mistakes
A common mistake is choosing 〜と only because English uses when. Japanese cares about the relationship between the two clauses: automatic result favors 〜と, while completed condition plus request or plan favors 〜たら.
Related Grammar
〜と
〜と is a conditional pattern used for natural results, automatic actions, directions, and repeated facts.
〜たら
〜たら is a flexible conditional pattern used for if, when, and after. It is common in daily conversation and works well with plans and requests.
〜ば
〜ば is a conditional pattern meaning if. It often focuses on the condition that must be true for something else to happen.
〜なら
〜なら is used when making a condition based on a topic, assumption, or information already mentioned. It often appears in advice and recommendations.
と・ば・たら・ならの違い
This comparison page organizes the four major Japanese conditionals と, ば, たら, and なら so learners can choose the right one.