Conditional Sentences

A Complete Guide to Conditional Sentences

Conditional sentences are used to describe situations where one event depends on another. They usually have two parts:

  • If clause – the condition
  • Main clause – the result

Example: If it rains (condition), I will stay home (result).

Types of Conditional Sentences

Zero Conditional (Facts and Truths)

Use: To express universal truths, scientific facts, or things that always happen.

Structure: If + Present Simple, Present Simple

  • If you heat water, it boils.
  • If it rains, the grass gets wet.
  • If people don’t sleep, they feel tired.

First Conditional (Real Possibility)

Use: For real or likely situations in the future.

Structure: If + Present Simple, will + base verb

  • If I study, I will pass the exam.
  • If it rains, we will stay home.
  • If she hurries, she will catch the bus.

Second Conditional (Unreal or Imaginary Present/Future)

Use: For imaginary or unlikely situations in the present or future.

Structure: If + Past Simple, would + base verb

  • If I had a car, I would drive to work.
  • If he were rich, he would travel the world.
  • If they knew the answer, they would tell us.

Third Conditional (Unreal Past)

Use: To express regret or imagine a different past result.

Structure: If + Past Perfect, would have + V3

  • If I had studied, I would have passed the test.
  • If she had left earlier, she would have caught the train.
  • If they had called me, I would have helped them.
Mixed Conditionals

Mixed conditionals are used when the time in the “if” clause and the main clause are different. They show how a past event can affect the present, or how a present situation could have changed the past.

Past Condition → Present Result

Structure: If + Past Perfect, would + base verb

  • If I had studied medicine, I would be a doctor now.
  • If she had gone abroad, she would live there today.

Present Condition → Past Result

Structure: If + Past Simple, would have + V3

  • If I were smarter, I would have chosen better.
  • If he knew the truth, he would have acted differently.
Important Notes
  • “If” can often be replaced by when, unless, as long as, provided that.
  • “Were” is used for all subjects in formal English — for example, “If I were you.”
  • Do not use “will” in the “if” clause; it is only used in the main clause.
  • Conditionals can be seen as combinations of time and possibility.
Summary
  • Zero Conditional: Real truth — (If + Present, Present)
  • First Conditional: Real future — (If + Present, will + V1)
  • Second Conditional: Unreal now/future — (If + Past, would + V1)
  • Third Conditional: Unreal past — (If + Past Perfect, would have + V3)

After reading this guide, you can confidently identify, use, and combine conditional sentences in any situation.