Conditionals · ESL grammar · Grammar · tenses · Verb

The Difference Between If and When

By Jacqueline Schaalje


When you use “if,” it means that the situation can happen or not.

If you say “when,” it’s certain the situation will happen.

So “if” means = in the situation that, or in case that.

And “when” means at the time that.

If and when can both be conditionals, which you can read more about here.

In this lesson, we’ll just practise when to use when and if, okay?

If or When?

Here are some examples. What would you use, if or when?

1 __________ we leave now, we can still be on time.

If or when?

If. Because you can leave now, or you can stay at home. There is a choice.

2 __________ you are ready, we’ll leave.

When. Because this means at the time that you’re ready. It doesn’t mean that the you in this sentence can choose to be ready or not. The question is just when he will be ready (at which time).

Let’s do some more.

3 _____________ I were the prime minister I would give everyone free ice cream on hot days.

If. This is an unreal situation which might be true one day (not very likely..), but it’s not a matter of what time this will happen.

4 I’ll call you _________ I get there.

When. The question is not whether this person will arrive at a certain place, but at what time. And at this time they will call.

When and If Are Both Okay

Of course there could also be sentences where you could use both if or when. But then the meaning will differ.

Here are some examples of this:

1 A If you’re ready, you can do this quiz.

1 B When you’re ready, you can do this quiz.

A presents a situation in which someone can be ready to do a quiz, or not be ready.

In B, the person is presumed to be ready at some point, but we don’t know what time that will be.

Here’s another one:

2 A If Auntie sends me a present, I will call her to thank her.

2 B When Auntie sends me a present, I will call her to thank her.

In A it’s not certain that Auntie sends a present. In B, Auntie will send a present, sure thing.

When and If Can Mean the Same

There is only one case in which if and when mean the same, and that is when you know the result of a situation.

Have a look at these examples:

3 A Thieves can come in when you leave the door open.

3 B Thieves can come in if you leave the door open.

Here it doesn’t matter whether you use “if” or “when,” because the thieves can come in at any time the door is open. The fact that I can have a choice to leave the door open or not is not important for the meaning of this sentence.

One more example of this:

4 A Chocolate melts when you heat it.

4 B Chocolate melts if you heat it.

The situation is not about whether I heat the chocolate or not, or the time I heat it. It’s about the result of heating the chocolate, which happens at any time I heat it.

Now you can do this online quiz.

La Vie – Picasso (1903)


Click here to do this quiz online and check your answers. 

Choose when or if.

1 Ok students, ___________ you know the answer, raise your hand.

2 ___________ I had had my butt kicked when I was younger, I’d now be a successful entrepreneur.

3 ___________ the tomatoes arrive at the packing station, they are first washed in lukewarm water.

4 I’m in heaven _______ she smiles at me.

5 ___________ you have enough information, you can start writing your essay.

6 I’d like to ask you something, __________ you don’t mind.

7 I’d like to point out a problem, __________ I may.

8 ____________ you like action movies, you’re sure to like Mission Impossible.

9 ____________ there’s anything I can do for you, let me know.

10 Did Picasso show a lot of promise __________ he was young?

Also check out this older (easier) quiz with if and when.

More about conditionals here.

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