We useifto introduce a possible or unreal situation or condition. We usewhento refer to the time of a future situation or condition that we are certain of:
You can only go inifyou’ve got your ticket.
WhenI’m older, I’d love to be a dancer.
| The speaker does not know whether Giles is coming back to the office. It is possible, but not definite. |
| The speaker is certain that Giles is coming back to the office. |
To talk about situations and conditions that are repeated or predictable, we can use eitheriforwhen+ present verb form:
You can driveifyou’re 17.
Ifyou don’t add enough wood, the fire goes out.
Whenwe go camping, we usually take two tents.
She gets out of breath easilywhenshe’s jogging.
Typical error
We don’t usewhento introduce possible or unreal situations:
Unfortunately,ifyou arrive too late, you are not allowed to take the exam because they don’t accept late enrolment.
Not: …when you arrive too late…