Conditionals: zero, first, second and third
Learn the zero, first, second and third conditionals in English with clear if clause rules, examples, common mistakes and a practice quiz.
In this lesson
Conditionals are sentences that talk about a condition and its result. They have two parts: an if clause (the condition) and a main clause (the result), as in If it rains, we will stay at home. English has four main types: the zero, first, second and third conditionals.
Key point
Choose the conditional by how real the situation is: zero for general truths, first for real future possibilities, second for unreal or unlikely situations, and third for unreal situations in the past.
What are the four types of conditionals?
Conditionals describe what happens, what could happen, what might have happened and what we wish would happen. They are sometimes called if clauses. This table shows the four main types at a glance.
| Type | If clause | Main clause | Example |
|---|---|---|---|
| Zero | If + simple present | simple present | If it rains, the ground gets wet. |
| First | If + simple present | will + base verb | If she studies, she will pass. |
| Second | If + simple past | would + base verb | If I won the lottery, I would buy a car. |
| Third | If + past perfect | would have + past participle | If she had studied, she would have passed. |
Tip
You can put either clause first. When the if clause comes first, use a comma: If it rains, we will stay at home. When the main clause comes first, do not use a comma: We will stay at home if it rains.
1. The zero conditional
We use the zero conditional when the time is now or always and the situation is real and possible. It is often used for general truths and facts. Both verbs are in the simple present tense: one in the if clause and one in the main clause.
If + simple present, … simple present
For example: If it rains, the crops grow. This is always true, so there cannot be a different result.
Examples
- If it rains, the ground gets wet.
- If James goes to the party with his friends, they sometimes get drunk.
- If Mary has a birthday party, she usually buys a new frock.
In the zero conditional, we can usually replace if with when without changing the meaning: When it rains, the ground gets wet.
2. The first conditional
We use the first conditional to talk about things that might happen in the future. It does not say what will definitely happen. It describes a possible condition and its probable result. The if clause is in the simple present, and the main clause uses the simple future tense.
If + simple present, … will + base verb
Examples
- If she studies, she will pass the exam.
- If you work hard, you will achieve your goals one day.
- If we practise cricket, we will win the match.
Common mistake
If it will rain tomorrow, we will stay at home. → If it rains tomorrow, we will stay at home. Do not use will in the if clause, even when you mean the future.
3. The second conditional
The second conditional uses the simple past tense after if, and would + base verb in the main clause. The past form does not mean past time here. It shows that the situation is unreal or unlikely.
If + simple past, … would + base verb
We use it for two kinds of situations.
Something in the present that is impossible because it is not true
For example: If I were the president of the country, I would develop it. I am not the president, so I cannot develop the country.
Examples
- If I knew how to swim, I would go to the Olympics.
- If I lived in India, I would speak Hindi.
- If he were sporty, he would join the army.
Something in the future that is possible but unlikely
For example: If I won the lottery, I would buy a new car. I will probably not win the lottery.
Examples
- If she got a transfer to her favourite school, she would work well.
- If she received some money, she would build her house.
- If they gave up their pride, they would live happily.
Note
With I, he, she and it, If I were is the traditional, more formal form. If I was is common in everyday speech. In exams and formal writing, use were.
4. The third conditional
The third conditional describes a situation that did not happen and imagines its result. The facts are the opposite of what the sentence says. It refers to an unreal past condition and its probable past result. It uses the past perfect tense after if, and would have + past participle in the main clause.
If + past perfect, … would + have + past participle
For example: If she had studied hard, she would have passed the exam. We know that she did not study hard, so she did not pass the exam.
Examples
- If she had been more careful, she would not have had an accident.
- If I had known him, I would have talked to him.
- If he had married a good girl, he would have lived a better life.
Common mistake
If I would have known, I would have helped. → If I had known, I would have helped. Would never goes in the if clause. You can check irregular past participles in our lesson on regular and irregular verbs.
How do you use unless?
Many negative conditional sentences can be written with unless instead of if … not. Unless means “except if”.
Examples
- If you don’t hurry, you will miss the bus. = Unless you hurry, you will miss the bus.
- If it doesn’t rain, the plants die. = Unless it rains, the plants die.
Common mistake
Unless you don’t hurry, you will miss the bus. → Unless you hurry, you will miss the bus. Unless already contains the idea of not.
To go further, read the Cambridge Dictionary grammar guide to conditionals with if, then try the British Council LearnEnglish lessons on zero, first and second conditionals and third and mixed conditionals.
Summary
- Every conditional has an if clause (the condition) and a main clause (the result).
- Zero: if + present, present. Use it for facts and general truths.
- First: if + present, will + base verb. Use it for real future possibilities.
- Second: if + past, would + base verb. Use it for unreal or unlikely situations.
- Third: if + past perfect, would have + past participle. Use it for unreal past situations.
Frequently asked questions
What is the difference between the first and second conditional?
The first conditional talks about a real possibility: If I see him, I will tell him. The second conditional talks about something unreal or unlikely: If I saw a ghost, I would scream.
Can I use will in the if clause?
Usually not. In first conditional sentences, the if clause uses the simple present: If it rains, not If it will rain. Will goes in the main clause.
Is it If I was or If I were?
Both are used. If I were is more formal and is the safer choice in exams. If I was is common in everyday conversation.
Do I always need a comma in a conditional sentence?
Only when the if clause comes first: If you call me, I will come. When the main clause comes first, there is no comma: I will come if you call me.
What does unless mean?
Unless means if not or except if. Unless you study, you will fail means the same as If you don’t study, you will fail.
Practise this lesson
5 questions
