What is a conditional?

Conditionals, also known as if clauses or conditional sentences, express a situation or condition and its possible result. They are made up of two clauses; the conditional clause and the main clause. The former usually starts with the word if and sets out a condition, while the latter expresses what happens when this condition is fulfilled. The main clause usually contains a modal verb such as will or would.

Harry will come to the party if he has time.
If I won the lottery, I would donate it all to charity.

Technically, there are four types of conditionals in English grammar: zero, first, second and third. Each one refers to a different context, although we can also construct mixed conditionals.


Mother: “Greg and I often bake cakes together.”

Greg: “Of course, if I have time, I help her.

Mother: “Greg, I actually want to make a cake this afternoon. Will you help me?”

Greg: “If I have time, I’ll help you.

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Mother: “Greg, I am going to make the cake now. Can you help me?”

Greg: “If I had time, I’d help you. But I have to do my homework.”

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Mother: “Now I’ve made the cake myself. Why didn’t you help me?”

Greg: “If I’d had time, I would have helped you. But I had to do my homework.”

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Comparing Conditionals

For a quick and handy overview of the different conditionals in English grammar, check out the table below. Scroll down for more detail on each one.

Type Form Example Explanation
Zero present + present If I have time, I help. general truth/repeated action
sometimes I have time
First present + will If I have time, I will help. realistic future possibility
I might have time later, it’s unsure
Second past + would If I had time, I would help. unreal possibility
I don’t have time and I can’t help
Third past perfect + would have if I had had time, I would have helped. imagined past situation
I didn’t have time and I couldn’t help

Zero Conditional

Zero conditional sentences express things that always happen providing that a certain condition is met.

If you leave ice cream in the sun, it melts.
If you heat water, it boils.

The zero conditional is formed by using the present tense in both the if-clause and the main clause.

Learn more about the zero conditional in English grammar.

First Conditional

The first conditional, also known as the real conditional, talks about future actions that can only take place under certain conditions. The if-clause expresses a condition that must be fulfilled in order for the future action in the main clause to occur.

If you study hard, you will pass the exam.
If it rains, we will cancel the picnic.

The if-clause contains a present tense, and the main clause contains a future tense (usually will + infinitive).

Learn more about the first conditional in English grammar.

Second Conditional

The second conditional talks about an unlikely or imaginary event and its result. It is therefore known as the unreal conditional.

If I knew the answer, I would tell you.
If she liked flowers, he would buy her some.

Second conditional if-clauses contain the past tense, while the main clause usually contains the modal verb would + infinitive.

Learn more about the second conditional in English grammar.

Third Conditional

The third conditional is also known as the impossible conditional: it looks back at past situations and their outcome and imagines them as different.

If she had booked her ticket sooner, it would have been cheaper.
I would have been impressed if he had baked the cake himself.

The if-clause contains the past perfect, while the main clause contains would have + past participle.

Learn more about the third conditional in English grammar.

Mixed Conditionals

We can mix the second and third conditionals to express an imagined past situation and its imagined present outcome.

If I had put on suncream this morning, I wouldn’t be sunburned now.

The reverse is also possible: when we use the second conditional in the if-clause and the third conditional in the main clause we imagine a present situation and an imagined past outcome.

If I spoke Mandarin, I would have done the translation myself.

Learn more about the tricky topic of mixed conditionals in English grammar and test yourself in the exercises.