What is the Zero Conditional?
The zero conditional is used to talk about facts, general truths, and situations that are always true. It describes what happens when something is a certain way—the result is certain and automatic. We use this structure for scientific facts, habits, and situations where cause and effect are always connected. The zero conditional is sometimes called the 'real conditional' because it expresses real, factual relationships.
Form and Structure
The zero conditional uses present simple in both the 'if' clause and the main clause. The pattern is: If + present simple, present simple. You can also reverse the order: Present simple + if + present simple. Both sentences mean the same thing. The 'if' in zero conditional means 'whenever' or 'always when' — it shows that something happens every time under certain conditions.
When to Use Zero Conditional
Use the zero conditional for three main situations: (1) Scientific and natural facts—'If you heat water to 100°C, it boils.' (2) General rules and habits—'If I wake up late, I skip breakfast.' (3) Instructions and procedures—'If you press this button, the door opens.' These statements are true in general; they don't depend on imagination or possibility. They're facts about how the world works.
Zero Conditional vs Other Conditionals
| Feature | Zero Conditional | First Conditional | Second Conditional |
|---|---|---|---|
| Form | If + present simple, present simple | If + present simple, will + infinitive | If + past simple, would + infinitive |
| When to use | To express facts, scientific truths, and situations that are always true. The result is 100% certain whenever the condition is met. | To talk about real and possible future situations. The result is likely but not guaranteed. | To talk about unreal, imaginary, or unlikely present/future situations. The result is hypothetical. |
| Positive example | If you heat water to 100°C, it boils. | If it rains tomorrow, I will take an umbrella. | If I had more time, I would learn Spanish. |
| Negative example | If plants don't get sunlight, they don't grow. | If she doesn't study, she won't pass the exam. | If I didn't live so far away, I wouldn't need a car. |
| Question example | What happens if you mix bleach and ammonia? | What will you do if you miss the bus? | What would you do if you won the lottery? |
| Certainty level | 100% certain — always true | Likely — possible and realistic | Unlikely or imaginary — not expected to happen |
| Key signal words | always, generally, every time, never, usually | tomorrow, next week, soon, probably, perhaps | wish, imagine, would, could, dream, in a perfect world |
| Time reference | Timeless — applies past, present, and future | Future — refers to a specific future possibility | Present or future — but unreal or contrary to fact |
| Typical topics | Science, nature, habits, universal rules, instructions | Plans, warnings, promises, predictions, advice | Wishes, daydreams, advice, polite requests, regrets about the present |
| 🔑 Key Difference: The zero conditional is the only conditional used for facts and general truths that are always true, regardless of time — both the condition and the result use the present simple to signal this timeless certainty. The first conditional shifts to will to indicate a real but uncertain future outcome, while the second conditional uses past tense forms and would to signal that the situation is imaginary, unlikely, or contrary to current reality. Choosing between them depends entirely on whether you are stating an unchanging truth, a realistic possibility, or a hypothetical scenario. | |||
Formula
✔ Positive
If
+
subject
+
verb (present simple)
+
object
+
subject
+
verb (present simple)
+
object
If it rains, the grass gets wet.
✖ Negative
If
+
subject
+
don't/doesn't
+
verb
+
object
+
subject
+
don't/doesn't
+
verb
If you don't study, you don't pass the test.
? Question
What
+
happens
+
if
+
subject
+
verb (present simple)
What happens if you mix red and blue paint?
Examples
If you add salt to water, it boils at a higher temperature.
Scientific fact · Present simple + present simple
If I eat too much sugar, I feel sick.
Personal habit · General truth about the speaker
Ice melts if it doesn't get kept in a freezer.
Natural fact · Negative zero conditional
When you freeze water, it becomes ice.
General truth · 'When' can replace 'if' in zero conditional
If the sun is very hot, we wear sunscreen.
Habitual action · Regular behavior in certain conditions
Babies cry if they are hungry.
General behavior · How things typically happen
When to use it
Science & Facts
Use zero conditional to explain scientific laws and how nature works. This is perfect for describing experiments and unchanging rules.
If you add an acid to a base, it neutralizes.
Habits & Routines
Describe what you regularly do in specific situations. This shows cause-and-effect in everyday life.
If I have free time, I go to the gym.
Instructions & Procedures
Give instructions or explain how things work mechanically. Each step has a predictable result.
If you press Ctrl+S, the document saves automatically.
Automatic Reactions
Explain what people naturally do in certain situations, without thinking about it.
If someone speaks loudly, people look at them.
Signal words
if
when
whenever
always
usually
generally
Common Mistakes
✕
Wrong
If you heat water, it will boil.
✓
Correct
If you heat water, it boils.
Zero conditional uses present simple in both clauses, not future tense.
✕
Wrong
If it rains, the ground became wet.
✓
Correct
If it rains, the ground becomes wet.
The zero conditional requires present simple in both clauses; mixing past tense 'became' with present tense 'rains' violates the consistency rule.
✕
Wrong
If you don't eat breakfast, you are tired.
✓
Correct
If you don't eat breakfast, you get tired.
Both are grammatically correct, but 'get tired' better expresses the result/change.
✕
Wrong
If I see him tomorrow, I tell him the news.
✓
Correct
If I see him, I tell him the news.
Zero conditional is for general facts, not future events. Use first conditional for 'tomorrow'.
KEY TAKEAWAYS
What to Remember
- Use present simple in both the if-clause and main clause.
- Zero conditional expresses facts and general truths where the result is always certain.
- Use it for scientific facts, habits, and situations with automatic cause-and-effect relationships.
- The zero conditional is called 'real conditional' because it describes factual, real situations.
- If the condition is true, the result always happens—there is no uncertainty.