When/If

What’s the difference between if and when?

When and if are easily confused; sometimes they are interchangeable but very often they have different meanings. Both words can talk about repeated actions, and both can express a condition. The key difference is that when refers to a fairly certain conditions in the future, while if introduces something uncertain, unlikely or hypothetical.

Learn the differences between if and when with Lingolia, then put your knowledge to the test in the free exercises.

Example

Whenever Jenny and Paul go on holiday, they always go to the sea.

When the wind conditions are right, Paul goes sailing.

If it’s sunny, Jenny will relax on the beach.

When it’s time to leave, they pack their bags and head to the train station.

If they lived by the sea, they would spend all their time at the beach.

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If

  • Use if for an action or event in the future that is uncertain.
Example:
If it’s sunny, Jenny will relax on the beach.

if = in case of or in the event that

  • Use if to introduce unlikely, hypothetical or unreal conditions in different conditional sentences.
Example:
If they lived by the sea, they would spend all their time at the beach.
if introduces a hypothetical condition
If the weather had been better, Paul would have gone sailing.
if introduces an impossible condition to imagine an alternative past (where the weather was good)

For more on conditional sentences see if clauses.

When

  • Use when to talk about an action or event in the future that you are certain will take place.
Example:
When it’s time to leave, they pack their bags and head to the train station.

We know that Jenny and Paul will eventually go home

Compare: if vs. when

To illustrate the difference between if and when, we can compare the following two sentences:

Compare:
I’ll call you when the plane lands. = normal sentence
I’m confident that the plane will land as expected
I’ll call you if the plane lands. = panic!
It’s 50/50 whether the plane will land or not!

If and When

We can use if or when + present verb to talk about repeated actions. In this case, if and when mean whenever (every time or at any time).

Example:
Whenever Jenny and Paul go on holiday, they go to the sea.
When the wind conditions are right, Paul goes sailing.
If it’s sunny, Jenny goes to the beach.

Want to learn about a related confusing word pair? Go to our page on if vs. whether.