Conditional Sentences | Examples & Use

A conditional sentence refers to a hypothetical situation and its possible consequence.

Conditional sentences always contain a subordinate clause that expresses a condition (e.g., ‘If it snows tomorrow’) and a main clause indicating the outcome of this condition (e.g., ‘school will be cancelled‘).

There are four main types of conditionals in English, each of which expresses a specific level of likelihood or possibility.

Types of conditional sentences

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How to use conditional sentences

Conditional sentences are used to describe a hypothetical scenario and the possible consequences of this scenario. All conditional sentences contain two clauses:

  • A subordinate clause that describes an unreal condition (e.g., ‘If you train more’)
  • A main clause that indicates the result of this hypothetical scenario (e.g., ‘you will become a better swimmer’)

The subordinate clause of a conditional sentence usually begins with the conjunction ‘if’.

This is often paired with a ‘then’ at the start of the second clause (e.g., ‘if you want to go, then you should go’). However, including ‘then’ is optional.

When the subordinate clause is used at the start of a sentence, it’s always followed by a comma. If the main clause comes first, no comma is needed (and ‘then’ should not be included).

Examples: How to form conditional sentences
  • If you ate healthier food, then you would have more energy.
  • You would have more energy if you ate healthier food.

If you switch the order of conditional clauses, you may also need to switch the order of the nouns and pronouns in the sentence.

Examples: Conditional clause order
  • If Tom had called earlier, he might have got an appointment.
  • Tom might have got an appointment if he had called earlier.
Note
While most conditional sentences use the conjunction ‘if’, expressions such as ‘provided that’, ‘so long as’, or ‘whether or not’ can also be used to express a condition (e.g., ‘So long as you fill the tank back up, you can borrow the car’).

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Zero conditional sentences

The zero conditional is used to indicate general truths, scientific facts, or habits. In zero conditional sentences, both the main clause and the conditional clause are normally in the present simple tense.

Zero conditional sentences can also use ‘when’ instead of ‘if’, because they refer to general truths rather than specific scenarios.

Example: Zero conditional sentences
If you don’t eat, you become hungry.

When you melt ice, it turns to water.

Zero conditionals can also be used to make a command or request or to give advice or instructions. In these instances, the conditional clause is in the present simple tense and the main clause is in the imperative mood.

Examples: Zero conditionals in the imperative mood
If you get lost, call me.

If you want to speak to a sales representative, dial ‘1’.

Note
While zero conditionals are most commonly formed using the present simple tense, other tenses can also be used to express logical implications. These sentences also count as zero conditionals (e.g., ‘If he was there on Thursday evening, it has major implications for our investigation’).

First conditional sentences

First conditional sentences refer to a possible action in the present and its realistic future consequence. Sentences using the first conditional contain two clauses:

  • A subordinate clause with a verb in the present simple tense (e.g., ‘if you eat’)
  • A main clause formed using a modal verb (usually ‘will’, ‘may’, ‘can’, or ‘might’) along with the infinitive form of the main verb (e.g., ‘run’)
Examples: First conditional sentences
If Laura sleeps any longer, she will miss the bus.

If you don’t practise guitar, then you won’t improve.

I can drive Nick to the airport if he needs a lift.

Tip
In first conditional sentences, ‘unless’ can be used instead of ‘if’ to create a negative conditional statement (e.g., ‘You won’t improve unless you practise guitar’).

Second conditional sentences

Second conditionals are used to refer to an improbable or impossible past or present condition and its unlikely or unrealistic future consequence. Sentences that use the second conditional contain two clauses:

  • A subordinate clause with a verb in the past subjunctive form (e.g., ‘looked’)
  • A main clause using a modal verb (usually ‘would’, ‘could’, or ‘might’) along with the infinitive form of the main verb (e.g., ‘sing’)
Examples: Second conditional sentences
If I were rich, then I would drive a different car every day.

If Bill talked less, he could finish more tasks.

Everyone would be unhappy if the flight were delayed.

Note
The past subjunctive form of the verb ‘be’ is ‘were’, regardless of the subject (e.g. ‘If I were you, I’d call in sick’). All other verbs in the past subjunctive are identical to their past simple forms.

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Third conditional sentences

Third conditional sentences are used to refer to an unreal past situation and its past result. Sentences that use the third conditional contain two clauses:

  • A subordinate clause with a verb in the past perfect tense (e.g., ‘if I had worked’)
  • A main clause using a modal verb (usually ‘would’, ‘could’, or ‘might’) along with the auxiliary verb ‘have’ and the past participle of the main verb
Examples: Third conditional sentences
If you hadn’t burned the pie, it would have tasted delicious.

If Sander had studied more, then he might have got a better grade.

I would have labelled the files more clearly if I had known they were important.

Mixed conditional

Mixed conditional sentences use a combination of the second and third conditionals. The first type of mixed conditional is used to refer to an unreal past condition and its ongoing consequence. Sentences that use the first type of mixed conditional contain two clauses:

  • A subordinate clause containing a verb in the past perfect tense (as in a third conditional)
  • A main clause with a modal verb (usually ‘would’) and the infinitive form of the main verb (as in a second conditional)
Examples: Type 1 mixed conditional sentences
If you had eaten your dinner, you wouldn’t be hungry.

You would know there was a meeting if you had read the email.

The second type of mixed conditional sentence is used to describe an unreal past condition and its past consequence. It’s formed using:

  • A subordinate clause with a verb in the past subjunctive form (as in a second conditional)
  • A main clause containing a modal verb (usually ‘would’) along with the auxiliary verb ‘have’ and the past participle of the main verb (as in a third conditional)
Examples: Type 2 mixed conditional sentences
If you paid attention in school, you would have learnt more.

I would have invited you if I knew you were free.

Common mistake: Adding ‘would’ to the ‘if’ clause

When using conditional sentences, people sometimes add the modal verb ‘would’ to the subordinate clause. While ‘would’ is often used in the main clause of second, third, or mixed conditional sentences, it’s wrong to add ‘would’ to the subordinate clause.

Instead, subordinate clauses in the second conditional always use the past subjunctive form, while subordinate clauses in the third conditional always use the past perfect form.

Examples: Modal verbs and conditionals
  • If you would drive to work, you would arrive earlier.
  • If you drove to work, you would arrive earlier.
  • If he would have asked first, I might have agreed.
  • If he had asked first, I might have agreed.

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Frequently asked questions

What is a conditional sentence?

A conditional sentence is a sentence that describes the possible consequences of a hypothetical situation.

Conditional sentences contain a subordinate clause that describes a hypothetical situation (usually starting with the conjunction “if”) and a main clause that describes its possible results (e.g., “If I were you, I’d buy a new phone”).

What is a conditional clause?

A conditional clause is one of two clauses in a conditional sentence.

Conditional clauses are subordinate clauses that refer to a hypothetical situation (usually starting with the conjunction “if”). They are used along with a main clause that describes the possible consequences of the hypothetical situation (e.g., “If you’re late again, you will be fired”).

Sources for this article

We strongly encourage students to use sources in their work. You can cite our article (APA Style) or take a deep dive into the articles below.

This Scribbr article

Ryan, E. (2023, September 11). Conditional Sentences | Examples & Use. Scribbr. Retrieved 9 April 2024, from https://www.scribbr.co.uk/verb/conditional-sentence/

Sources

Aarts, B. (2011). Oxford modern English grammar. Oxford University Press.

Butterfield, J. (Ed.). (2015). Fowler’s dictionary of modern English usage (4th ed.). Oxford University Press.

Garner, B. A. (2016). Garner’s modern English usage (4th ed.). Oxford University Press.

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Eoghan Ryan

Eoghan has a lot of experience with theses and dissertations at bachelor's, MA, and PhD level. He has taught university English courses, helping students to improve their research and writing.