Zero Conditional

Form

In zero conditional sentences, the tense in both parts of the sentence is the simple present.

If clause (condition)	Main clause (result)
If + simple present	simple present
If this thing happens	that thing happens.

As in all conditional sentences, the order of the clauses is not fixed. You may have to rearrange the pronouns and adjust punctuation when you change the order of the clauses, but the meaning is identical. In zero conditional sentences, you can replace "if" with "when", because both express general truths. The meaning will be unchanged.

Examples

If you heat ice, it melts.
Ice melts if you heat it.
When you heat ice, it melts.
Ice melts when you heat it.
If it rains, the grass gets wet.
The grass gets wet if it rains.
When it rains, the grass gets wet.
The grass gets wet when it rains.

Function

The zero conditional is used to make statements about the real world, and often refers to general truths, such as scientific facts. In these sentences, the time is now or always and the situation is real and possible.