Overview — The Four Conditionals

0

Zero Conditional

General truths & facts

1

First Conditional

Real or likely future situations

2

Second Conditional

Imaginary present or future

3

Third Conditional

Imaginary past — didn't happen

Zero Conditional

General truths · Scientific facts · Things always true

IF / WHEN + Present Simple , Present Simple

We use the zero conditional to talk about things that are always true — facts, habits, or natural laws. IF and WHEN are interchangeable in this structure.

If you heat water to 100°C, it boils.

Scientific fact

If it rains, the streets get wet.

Always true

When I'm tired, I make mistakes.

Personal habit

First Conditional

Real situations · Likely future results

IF + Present Simple , will / can / may + infinitive

Use the first conditional when the situation is real or possible and the result is likely to happen. The IF clause is in the present — never use 'will' after 'if'.

If you study hard, you will pass the exam.

Likely future result

If it rains tomorrow, we'll stay inside.

Real possibility

If she calls, I can ask her directly.

Using 'can' instead of 'will'

Watch out: Never say "if I will go" — always use the present tense after IF.

Second Conditional

Imaginary or unlikely situations in the present / future

IF + Past Simple , would / could + infinitive

Use the second conditional when the situation is imaginary, unlikely, or impossible — now or in the future. After 'If I', use 'were' (not 'was') in formal English.

If I won the lottery, I would travel the world.

Unlikely, but imagined

If I were you, I would study more.

'Were' — formal advice

If she had more time, she could learn Spanish.

Using 'could' instead of 'would'

Watch out: Don't mix tenses — "If I would have time, I will call you" is a common mistake.

Third Conditional

Imaginary past situations · Regrets · Things that didn't happen

IF + Past Perfect , would / could / might + have + past participle

Use the third conditional to imagine a different past. The situation did NOT happen.
would have → certain imaginary result · might have → less certain · could have → unused ability.

If I had studied, I would have passed.

Regret — didn't study

If she hadn't left early, she might have met him.

Less certain result

If we'd taken a taxi, we could have arrived on time.

Ability not used

Watch out: Never put 'would' in the IF clause — "If I would have studied" is wrong.

First vs Second — What's the difference?

A common source of confusion for B2 learners

First · It COULD happen

If I have time, I'll call you.

→ Maybe I'll have time. Real possibility.

If she studies, she'll pass.

→ She might study. Likely outcome.

Second · It probably WON'T happen

If I had more time, I would call you.

→ I don't have time now. Imaginary.

If she studied, she would pass.

→ She doesn't study. Unreal.

Quick Reference — All Four Conditionals

0

If + Present Simple, Present Simple

General truths

1

If + Present Simple, will + inf

Real / likely future

2

If + Past Simple, would + inf

Imaginary present/future

3

If + Past Perfect, would have + pp

Imaginary past

Common Mistakes — FCE Traps

Errors that consistently appear in Cambridge exam writing

If I will see her, I'll tell her.

→

If I see her, I'll tell her.

Never use 'will' after 'if' in the conditional clause

She would passed the exam.

→

She would pass the exam.

Use bare infinitive after 'would'

If I was you...

→

If I were you...

'Were' is the formal second conditional form

They would have catched the train.

→

They would have caught the train.

Irregular past participle

If he wouldn't have gone...

→

If he hadn't gone...

No 'would' in the IF clause, ever

Your turn

Answer out loud — full sentences

Use all four conditionals.

1

What happens if you don't sleep enough?

2

What will you do if it rains this weekend?

3

What would you do if you could live anywhere?

4

Tell me one thing you would have done differently last year.

Summary

Zero

IF + present, present

General truths and facts

First

IF + present, will + inf

Real or likely future situations

Second

IF + past, would + inf

Imaginary present or future

Third

IF + past perfect, would have + pp

Imaginary past — didn't happen