Conditional Clauses in English Grammar

Introduction

Conditional clauses, also known as if clauses or conditional sentences, express an imagined situation or condition and the possible result of that situation. They consist of a main clause and a conditional dependent clause. Conditional clauses are often introduced by the word if, although sometimes other words can be used. Check out our pages on conjunctions and if or when for more information.

Learn about the different types of conditional sentences in English grammar, then test out your grammar skills in the exercises.

Example

Mother: “Greg, I 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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Usage and Construction

First Conditional

We use the first conditional to talk about an action that could take place under certain conditions in the present or the future. It is also called the real conditional because it reflects a realistic possibility.

To construct the first conditional, use the formula: if + present simple, will + infinitive.

Example:
If I have time, I will help you.

It is possible that I will have time.

Second Conditional

We use the second, or unreal, conditional to talk about present or future situations that are unrealistic – they are untrue or unlikely to become true in the future.

To construct the second conditional, use the formula: if + simple past, would + infinitive

Example:
If I had time, I would help you.

I already know that I won’t have time.

If I was/were you …

When the be is used in unreal conditional clauses, we can use both was and were for the first person singular.

Example:
If I were you, I would not do this.
I wouldn’t do that if I was you.

Third Conditional

We use the third conditional to talk about a past condition and its outcome. The third conditional express an impossible condition – we cannot go back in time to change the outcome.

To construct the third conditional use the formula: if + past perfect, would have + past participle

Example:
If I had had time, I would have helped you.

I did not have time and I did not help you – this cannot be changed.

Modal Verbs in Conditional Sentences

In place of will/would in conditional sentences, we can use use other modal verbs. However, using other verbs changes the meaning of the sentence.

Example:
If I have time, I can/could/may/might help you.
If I had time, I could/might help you.
If I had had time, I could/might have helped you.

Notes on Sentence Structure

We can change the order of the two clauses. When the sentence starts with the if clause, we put a comma before the main clause.

Example:
If I have time, I will help you.
If I had time, I would help you.
If I had had time, I would have helped you.

When the sentence starts with the main clause, we don’t use a comma.

Example:
I will help you if I have time.
I would help you if I had time.
I would have helped you if I had had time.

Learn more about punctuation and comma usage in the writing school section of the website.