когда vs если

kogda vs yesli — when vs if

What it really means

Когда means "when" and introduces a time relationship: one event happens at the time of another, whether the event is certain or expected. Если means "if" and introduces a condition: the result depends on whether something happens. The choice is about time versus uncertainty/condition, not simply about verb tense.

In future subordinate clauses, Russian uses present-form morphology after когда rather than English-style "will." The verb may be perfective when the completed event is the time marker: "Когда я приду, позвоню" (When I arrive, I will call). After если, use the form that matches the meaning: "Если будет дождь, останемся дома" (If it rains, we will stay home).

Examples in natural speech

Когда я приду, мы поговорим.
When I arrive, we will talk.
Позвони, когда будешь дома.
Call when you are home.
Если будет дождь, мы останемся дома.
If it rains, we will stay home.
Если хочешь, я помогу.
If you want, I will help.
Когда он был маленьким, он жил здесь.
When he was little, he lived here.
Если он позвонит, передай мне трубку.
If he calls, put him through to me.

Common mistakes

Do not use когда for a hypothetical condition: "Когда будет дождь" normally means when the rain comes, not if it rains. Do not put буду after когда or если for ordinary future subordinate clauses; use present forms such as когда приду and если будет.

Memory tip

Когда schedules an event in time; если makes the result depend on a condition.

Frequently asked questions

What is the difference between когда and если in Russian?

Когда means when and links events in time. Если means if and introduces a condition whose result may or may not happen.

How do you say when I arrive in Russian?

Say "когда я приду" or "когда я приеду." Russian normally uses a present-form verb after когда for a future subordinate event, not буду.

Can когда mean if in Russian?

In some contexts когда can sound like "when" with an event treated as expected, but it does not normally replace если. Use если when the condition is genuinely uncertain or hypothetical.

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