Conditional Sentences | Types, Use & Examples

A conditional sentence describes a hypothetical situation and its potential consequence.

Conditional sentences always include both a dependent clause (also known as a subordinate clause) and an independent clause (also known as a main clause).

The dependent clause expresses a condition (e.g., “If I drink coffee”), and the independent clause describes the result of the condition (e.g., “I will be awake all night”).

In English, there are four primary types of conditionals, corresponding to different levels of possibility or likelihood.

TypeFunctionExample

Conditional sentence types
Zero conditional Expresses a general truth If you press this button, the car unlocks.
First conditional Expresses a likely future consequence If you take some medicine, you will feel better.
Second conditional Expresses an unrealistic or unlikely future consequence If I won the lottery, I would buy a mansion.
Third conditional Expresses an unreal past situation and its result If you had listened to me, you would not have missed your train.

Using conditional sentences

Conditional sentences are used to refer to a hypothetical scenario and its potential consequences. Every conditional sentence is made up of two clauses:

  • A dependent clause (sometimes referred to as a conditional clause) that describes a condition that is unreal or has not yet happened (e.g., “If you study”)
  • An independent clause that describes the result of the hypothetical condition (e.g., “you will pass the test”)

The conjunction “if” is usually used at the beginning of the conditional clause. The independent clause sometimes begins with “then” (e.g., “If you go skiing, then you will need to buy goggles”), but including “then” is not required.

If the dependent clause is placed at the beginning of the sentence, a comma is required after the clause. However, if the independent clause appears first, no comma is required (and “then” should not be used).

Conditional sentence examples
  • If you had a dog, then you would get more exercise.
  • You would get more exercise if you had a dog.

When the order of the clauses in a conditional sentence is changed, the nouns and pronouns may also need to be changed.

Conditional clause pronoun examples
  • If Irene worked harder, she would be promoted.
  • Irene would be promoted if she worked harder.
Note
Although the conjunction “if” is the most common way to express a conditional, other expressions such as “whether or not,” “provided that,” and “so long as” can also be used (e.g., “Provided that the document is short, I can edit it by tomorrow”).

Zero conditional sentences

The zero conditional is used when communicating facts, habits, or general truths. The independent clause and the conditional clause are generally in the simple present tense in zero conditional sentences.

Because zero conditional statements refer to general truths rather than specific scenarios, “when” can be used instead of “if” in the conditional clause.

Zero conditional examples
If the red light is on, the battery needs to be charged.

When you open this door, an alarm sounds.

When zero conditionals are used to give advice or instructions or to make a command or request, the simple present tense is used for the conditional clause and the imperative mood is used for the independent clause.

Imperative mood zero conditional examples
If the timer goes off, take the cookies out of the oven.

If you have a raincoat, bring it with you.

Note
Logical implications can also be expressed using the zero conditional. In these cases, other tenses than the simple present tense may be used (e.g., “If Ellie saw Paul at the soccer game, that means he was not sick after all”).

First conditional sentences

First conditional sentences indicate a realistic potential action in the present and its probable result. The two clauses of a first conditional sentence follow a specific pattern:

  • The conditional clause contains a verb in the simple present tense (e.g., “if it rains”).
  • The independent clause contains a modal verb (usually “will,” “might,” “may,” or “can”) and the infinitive form of the main verb (e.g., “walk”).
First conditional examples
You will be late if you wait for a taxi.

If I don’t eat soon, I might faint.

Maya can go if she finishes her homework.

Note
You can use “unless” instead of “if” to form a negative conditional sentence (e.g., “Unless I eat soon, I might faint”).

Second conditional sentences

The second conditional is used when referring to an impossible or improbable present or past condition and its unrealistic or unlikely result. The two clauses of a second conditional sentence follow a specific pattern:

  • The conditional clause contains a past subjunctive verb form (e.g., “snowed”).
  • The independent clause contains a modal verb (usually “would,” “might,” or “could”) and the infinitive form of the main verb (e.g., “play”).
Second conditional examples
If Dante talked more, he would make more friends.

If I were braver, I would go skydiving.

We would all celebrate if our teacher canceled class.

Note
The past subjunctive form of the verb “be” is “were” for all subjects (e.g., “If she were smart, she would invest her money”). The past subjunctive form of all other verbs is the same as the simple past form.

Third conditional sentences

The third conditional is used when describing an unreal past condition and its past consequence. The two clauses of a third conditional sentence follow a specific pattern:

  • The conditional clause contains a past perfect tense verb (e.g., “if I had known”).
  • The independent clause contains a modal verb (usually “would,” “might,” or “could”), the auxiliary verb “have,” and the past participle of the main verb (e.g., “play”).
Third conditional examples
If Cora had started on time, she would have finished by now.

I might have attended the play if I had heard about it.

We would have won the game if they hadn’t cheated.

Mixed conditional sentences

Mixed conditional sentences combine the second and third conditionals. There are two types of mixed conditionals. The first type describes an unreal past condition and its ongoing result. The two clauses of this type of mixed conditional sentence follow a specific pattern:

  • The conditional clause is formed like the third conditional, with a past perfect tense verb.
  • The independent clause is formed like the second conditional, with a modal verb (usually “would”) and the infinitive of the main verb.
Type 1 mixed conditional examples
If I had purchased stocks, I would be rich.

We would own a house if we had qualified for a loan.

The second type of mixed conditional sentence refers to an unreal past condition and its past result. The two clauses of this type of mixed conditional sentence follow a specific pattern:

  • The conditional clause is formed like the second conditional, with a verb in the past subjunctive form.
  • The independent clause is formed like the third conditional, with a modal verb (usually “would”), the auxiliary verb “have,” and the past participle of the main verb.
Type 2 mixed conditional examples
If I were free, I would have gone to the party.

You would have enjoyed the flight if you flew first class.

Common error: Including “would” in the “if” clause

People sometimes make the mistake of adding “would” to the dependent clause (the “if” clause) of conditional sentences. Although it is correct to use “would” in the independent clause of second, third, or mixed conditional sentences, it is incorrect to use it in the dependent clause.

Subordinate clauses always use the past subjunctive form of the verb in the second conditional and the past perfect form in the third conditional.

Modal verbs and conditionals examples
  • If you would wake up earlier, you would have time to exercise.
  • If you woke up earlier, you would have time to exercise.
  • If I would have known about the dress code, I would have worn a suit.
  • If I had known about the dress code, I would have worn a suit.

Frequently asked questions about conditional sentences

What is a conditional clause?

A conditional clause is one of the two clauses used in a conditional sentence. It is a type of dependent clause (also known as a subordinate clause) that describes a hypothetical situation.

Conditional clauses typically begin with the conjunction “if.” They are connected to an independent clause (also called a main clause) that describes the potential results of the hypothetical scenario (e.g., “If it snows, school will be canceled).

What is the first conditional?

The first conditional is a type of conditional sentence that describes a realistic potential action in the present and its probable result (e.g., “If you try your best, you will succeed”).

All first conditional sentences are made up of two clauses:

A dependent clause that contains a verb in the simple present tense (e.g., “if you try”).
An independent clause that contains a modal verb (usually “will,” “might,” “may,” or “can”) and the infinitive form of the main verb (e.g., “succeed”).

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Kayla Anderson Hewitt, MA

Kayla has a master's degree in teaching English as a second language. She has taught university-level ESL and first-year composition courses. She also has 15 years of experience as an editor.