The 4 Types of Conditional Sentences

Want to talk about hypothetical situations, future possibilities, or past regrets? You need a conditional sentence!
Conditional sentences let us express ‘if’ scenarios – things that could happen, things that could have happened, or things we wish were different. They’re incredibly useful when you’re talking about possibilities, cause and effect, or even just dreaming about what you’d do if you won the lottery!
Let’s discuss what conditional sentences are, the different types, their grammar rules and how to use them correctly in your writing.
What Is a Conditional Sentence?
A conditional sentence describes an event that can happen only if a certain condition is true.
Conditional sentences contain a subordinate clause that describes the condition (e.g. If I study hard) followed by a main clause that describes the results of the condition (I will pass the exam).
There are different types of conditional sentences depending on how likely the event is or when the condition applies (past, present, or future).

The Four Types of Conditional Sentences
There are four main types of conditional sentences: zero, first, second, and third. Each type expresses a different level of possibility or certainty.

1. Zero Conditional (General Truths)
The zero conditional is used when the result of the condition is always true. It’s perfect for expressing facts, universal truths, or things that happen regularly.
Structure:
If + present simple, … present simple.
Examples:
• If water reaches 100°C, it boils.
• If you heat ice, it melts.
Remember, the zero conditional is about things accepted as always true or to express a logical consequence e.g ‘On Saturdays, I don’t work’.
Although both clauses usually use the present simple tense in this type, the main clause can also be in the imperative mood, for example, ‘text me’ in the conditional sentence: ‘If you can’t find it, text me’.

2. First Conditional (Real Future Possibilities)
First conditional sentences are used for real, possible situations that could happen in the future. The condition describes something that’s likely to happen, and the result describes what will happen if the condition is met.
Structure:
If + present simple, … will + infinitive.
Examples:
• If it rains tomorrow, we will cancel the picnic.
• If you study hard, you will pass the exam.
The examples here are likely scenarios. If it does rain, it will very likely prevent the picnic from going ahead.
Remember, the zero conditional is used to express general truths, while the first conditional describes situations that might happen.

3. Second Conditional (Unreal Present or Future)
The second conditional is for unreal or unlikely situations. These are hypothetical events that probably won’t happen, or they’re wishes about the present or future.
Structure:
If + past simple, … would + infinitive.
Examples:
• If I won the lottery, I would travel the world.
• If I were you, I would apply for the job.
Even though we’re talking about the present or future, we use the past simple tense to express unreality. For example, we say ‘If I were you’ (not ‘was’) – this is because ‘were’ is used in hypothetical statements.

4. Third Conditional (Unreal Past)
The third conditional is for talking about hypothetical situations in the past—things that didn’t actually happen. It’s perfect for expressing regrets or imagining how things might have turned out differently.
Structure:
If + past perfect, … would have + past participle.
Examples:
• If I had studied harder, I would have passed the test.
• If we had left earlier, we wouldn’t have missed the flight.
Use the third conditional for things that didn’t happen in the past and their imaginary consequences.

Mixed Conditionals: When Two Time Periods Collide
Mixed conditionals can be confusing, but once you get the hang of them, they’re actually pretty logical! They are used when the condition and the result refer to different time periods. In other words, mixed conditionals combine parts of the second and third conditional to talk about how an unreal past event affects the present or how an unreal present situation could have affected the past.
There are a few different ways you can mix conditionals, but here are the two main types:
1. Present Result of a Past Condition
This type of mixed conditional talks about an unreal past event and its hypothetical consequence in the present. You use it when you want to talk about how something that didn’t happen in the past is affecting your current reality.
Structure:
If + past perfect, … would + infinitive.
Examples:
• If I had studied harder in school, I would have a better job now.
• If we had taken the earlier flight, we would be home by now.
In these sentences, we’re talking about a past event that didn’t happen (e.g., not studying harder, not taking the earlier flight), and how that affects the present (e.g., not having a better job, not being home yet).
2. Past Result of a Present Condition
This type of mixed conditional talks about a present situation and how it would have affected a past event. You use it when you want to express that something happening now would have changed something in the past if the present condition were true.
Structure:
If + past simple, … would have + past participle.
Examples:
• If I were more organised, I would have finished the project on time.
• If she were richer, she would have bought that house last year.
Here, we’re talking about a current situation (e.g., not being organised, not being rich) and how that would have changed something in the past (e.g., finishing the project, buying the house).
Common Mistakes with Conditional Sentences
1. Mixing Up Tenses
One of the most common mistakes is mixing up the tenses in conditional sentences. Remember to follow the correct structure for each type of conditional.
Wrong: If I will see him, I will tell him.
Right: If I see him, I will tell him.
2. Using ‘Would’ in the If-Clause
In English, you never use ‘would’ in the if clause. Save ‘would’ for the result clause.
Wrong: If I would have known, I would have called you.
Right: If I had known, I would have called you.
3. Confusing Second and Third Conditionals
The second and third conditionals are often confused. Use the second conditional for unreal present/future scenarios, and the third for unreal past situations.
Think you know your conditional sentences? Test your knowledge by taking a quiz!

FAQs About Conditional Sentences
1. Can I use ‘when’ instead of ‘if’ in conditional sentences?
Yes, but only in certain situations. ‘When’ can be used instead of ‘if’ in zero conditional sentences when the outcome is always certain or inevitable.
• If you heat water to 100°C, it boils. (Correct)
• When you heat water to 100°C, it boils. (Correct)
However, in hypothetical or future situations, you should stick to ‘if’.
2. What’s the difference between ‘if’ and ‘whether’?
‘If’ is typically used for conditional sentences, while ‘whether’ is used when presenting two alternatives.
• If you’re coming to the party, let me know. (conditional)
• Let me know whether you’re coming to the party or not. (alternative)
3. Can you use ‘would’ in the if-clause?
No, ‘would’ should never be used in the if-clause. It is used in the result clause of second and third conditional sentences.
• If I were rich, I would buy a mansion. (Correct)
• If I would be rich, I would buy a mansion. (Incorrect)
Ready To Write Your Conditional Sentences?
Conditional sentences are a powerful way to express cause and effect, hypothetical situations, and future possibilities.
Now that you’ve got the hang of conditional sentences, why not try writing a few of your own? Just remember to follow the correct structure and grammar rules, and you’ll be able to add nuance and depth to your writing!