First, Second and Third Conditionals: Rules and Exercises

The if-clause can usually come first or second.

If I finish early, I will call you.

I will call you if I finish early.

When the if-clause comes first, use a comma before the main clause.

Zero conditional

Use the zero conditional for facts, rules, routines and results that are generally or always true.

The usual structure is:

if + present simple, present simple

If you mix blue and yellow, you get green.

If I drink coffee late, I cannot sleep.

Plants die if they do not get enough water.

Both parts describe a general relationship rather than one particular future event.

You can often replace if with when without changing the basic meaning:

When you heat water to 100°C, it boils.

If you heat water to 100°C, it boils.

The zero conditional is also useful for instructions:

If the screen freezes, press this button.

‍

First conditional

Use the first conditional for a real or realistic future possibility.

The usual structure is:

if + present simple, will + base verb

If I finish work early, I will meet you.

She will be late if the traffic is bad.

If you practise regularly, your English will improve.

The condition is possible. We do not know whether it will happen, but we consider it realistic.

First conditional with other modal verbs

The main clause does not have to use will. Other modal verbs can express possibility, permission, advice or obligation.

If you finish early, you can leave.

If the weather gets worse, we might cancel the trip.

If you feel ill, you should see a doctor.

Do not normally use will after if

Incorrect:

If it will rain, we will stay inside.

Correct:

If it rains, we will stay inside.

The present simple in the if-clause refers to a possible future condition.

‍

Second conditional

Use the second conditional for hypothetical, unlikely or imaginary situations in the present or future.

The usual structure is:

if + past simple, would + base verb

If I had more free time, I would exercise more.

She would travel around the world if she won the lottery.

If we lived closer, we would see each other more often.

Although the if-clause uses a past form, the meaning is usually present or future.

First vs second conditional

Compare:

If I get the job, I will move to London.

This is a realistic future possibility.

If I got the job, I would move to London.

This sounds more hypothetical or uncertain.

The difference is often the speaker's view of how realistic the situation is.

Were in hypothetical situations

With the verb be, were can be used with all subjects in formal or careful English:

If I were you, I would apologise.

If she were here, she would know what to do.

In everyday English, was is also common with I, he, she and it, but if I were you is the standard fixed expression.

‍

Third conditional

Use the third conditional to imagine a different past.

The structure is:

if + past perfect, would have + past participle

If I had left earlier, I would have caught the train.

She would have passed the exam if she had studied more.

If they had checked the address, they would not have got lost.

The situation cannot now be changed because it belongs to the past.

The third conditional is often used for:

• regrets
• criticism
• missed opportunities
• imagined alternative results

If I had known, I would have helped.

You would not have missed the flight if you had arrived earlier.

Second vs third conditional

The second conditional imagines a different present or future:

If I had more money, I would travel more.

The third conditional imagines a different past:

If I had had more money last year, I would have travelled more.

Notice the unusual form had had. The first had is the auxiliary verb, while the second is the past participle of have. The third conditional requires the past perfect in the if-clause. Review our past perfect vs past simple guide if you need more practice distinguishing earlier and later past events.

Mixed conditionals

Mixed conditionals combine parts of the second and third conditionals when the condition and result refer to different times.

Past condition + present result

Use this when a past event explains a present situation.

If I had studied medicine, I would be a doctor now.

The studying belongs to the past, but the result is about the present.

Structure:

if + past perfect, would + base verb

Another example:

If we had moved to London, we would live there now.

Present condition + past result

Use this when a present characteristic explains a past result.

If I were more organised, I would not have missed the deadline.

Being disorganised is a present characteristic. Missing the deadline happened in the past.

Structure:

if + past simple, would have + past participle

Mixed conditionals are particularly useful when explaining causes and consequences across different time periods.

Once you are comfortable with the main conditional types, continue with conditionals using unless, provided that and as long as for more advanced ways to express conditions.

‍

Choosing the correct conditional

Ask yourself two questions.

1. What time am I talking about?

• general truth → zero conditional
• possible future → first conditional
• imaginary present or future → second conditional
• imaginary past → third conditional

2. How real is the situation?

Compare:

If she calls, I will tell her.

The speaker believes the call is realistically possible.

If she called, I would tell her.

The speaker sees the situation as more hypothetical.

The grammar reflects the speaker's attitude towards reality and possibility.

‍

Common mistakes

Using will in the if-clause

Incorrect:

If I will see him, I will tell him.

Correct:

If I see him, I will tell him.

Confusing first and second conditional forms

Incorrect:

If I had more time, I will study more.

Correct:

If I had more time, I would study more.

Using would in both clauses

Incorrect:

If she would practise more, she would improve.

Correct:

If she practised more, she would improve.

Using the wrong form in the third conditional

Incorrect:

If I would have known, I would have helped.

Correct:

If I had known, I would have helped.

Forgetting the past participle

Incorrect:

She would have went.

Correct:

She would have gone.

Treating all past forms as past time

In the second conditional, the past simple often describes a hypothetical present or future situation:

If I lived in Spain, I would learn Spanish.

This does not necessarily mean that the speaker lived in Spain in the past.

‍

Exercises and answers

Choose the correct verb forms.

1. If you heat ice, it __________. (melt)
2. If it __________ tomorrow, we will cancel the picnic. (rain)
3. If I __________ more money, I would buy a larger flat. (have)
4. She would have passed if she __________ harder. (study)
5. If you do not hurry, you __________ the train. (miss)
6. If I __________ you, I would speak to the manager. (be)
7. If they had left earlier, they __________ on time. (arrive)
8. If people eat too much, they often __________ weight. (gain)
9. We might go to the beach if the weather __________ better. (get)
10. If he __________ closer, we would visit him more often. (live)
11. I would have called you if I __________ your number. (have)
12. If she had accepted the job, she __________ in Paris now. (live)
13. If I were more careful, I __________ that mistake yesterday. (not make)
14. If the alarm __________, leave the building immediately. (sound)
15. What would you do if you __________ the lottery? (win)

Answers and explanations

1. melts
   This is a general scientific fact, so use the zero conditional.
2. rains
   Use the present simple after if in the first conditional.
3. had
   This is an imaginary present situation, so use the second conditional.
4. had studied
   The condition refers to an unreal past situation, so use the past perfect.
5. will miss
   This is a realistic future consequence.
6. were
   If I were you is the standard hypothetical form.
7. would have arrived
   This is the result of an unreal past condition.
8. gain
   The sentence describes a general result, so use the zero conditional.
9. gets
   Use the present simple in the condition even though the meaning is future.
10. lived
    The situation is hypothetical, so use the second conditional.
11. had had
    The condition belongs to the past and requires the past perfect of have.
12. would live
    This is a mixed conditional: a past decision produces a hypothetical present result.
13. would not have made
    A present characteristic is linked to a past result.
14. sounds
    This is an instruction based on a possible or repeated condition.
15. won
    This is an imaginary future situation, so use the second conditional.

The four main types of conditionals express different relationships between a condition and its result. Use the zero conditional for general truths, the first conditional for realistic future possibilities, the second conditional for hypothetical present or future situations, and the third conditional for imaginary past situations. Mixed conditionals allow you to connect causes and results across different times.

Related grammar lessons

• Modal Verbs in English: Uses and Exercises
• Past Perfect vs Past Simple: Rules and Exercises
• Conditionals with Unless, Provided That and As Long As