What is the Zero Conditional?
The zero conditional is used to describe facts, general truths, and things that always happen under certain conditions. It expresses automatic or inevitable consequences—situations where the result is always the same. The structure is simple: if + present simple tense in the condition, and present simple tense in the main clause. This grammar is called "zero" because there is zero probability of the result being different; it always happens.
Key Characteristics
The zero conditional describes timeless facts and scientific rules rather than imaginary or unlikely situations. Both clauses use the present simple tense, making it straightforward and logical. The condition and result are not about the future or the past—they are about how things work in general. You can also switch the order of the clauses without changing the meaning: 'Water boils if you heat it to 100°C' means the same as 'If you heat water to 100°C, it boils.'
Zero Conditional vs Other Conditionals
| Dimension | Zero Conditional | First Conditional | Second Conditional | Third Conditional |
|---|---|---|---|---|
| Form | If + present simple, present simple | If + present simple, will + infinitive | If + past simple, would + infinitive | If + past perfect, would have + past participle |
| When to use | Facts, general truths, scientific laws, habits, and things that always happen as a result of a condition | Real and likely future situations; things that are possible or probable if the condition is met | Unreal, imaginary, or hypothetical present/future situations; unlikely or impossible conditions | Unreal or hypothetical situations in the past; imagining a different outcome for something that already happened |
| Probability | Certain / always true (100%) | Likely / possible (real chance it will happen) | Unlikely / hypothetical (not expected to happen) | Impossible / counterfactual (the moment has already passed) |
| Time reference | Present / general / timeless | Present → Future | Present / Future (unreal) | Past (unreal / counterfactual) |
| Positive example | If you heat ice, it melts. | If it rains, I will take an umbrella. | If I had more money, I would travel the world. | If she had studied harder, she would have passed the exam. |
| Negative example | If you don't water plants, they don't survive. | If he doesn't hurry, he won't catch the bus. | If I didn't have a car, I wouldn't drive to work. | If they hadn't left early, they wouldn't have avoided the traffic. |
| Question example | What happens if you mix bleach and ammonia? | What will you do if you miss the flight? | Where would you live if you could choose any country? | What would you have done if you had known the truth? |
| Key signal words | always, generally, every time, usually, never | will, might, can, going to, probably, possibly | would, could, might (+ infinitive), imagine, suppose | would have, could have, might have, if only, had (inverted form) |
| Emotional tone | Neutral, factual, instructional | Practical, planning-oriented, motivating | Imaginative, wishful, speculative | Reflective, regretful, analytical |
| Common uses | Science lessons, instructions, recipes, universal truths | Plans, warnings, promises, predictions, negotiations | Daydreaming, polite requests, advice, creative writing | Regret, criticism, analysing past decisions, storytelling |
| 🔑 Key Difference: The zero conditional describes universal truths and automatic results that are always true regardless of time — the condition and result are inseparable facts. The first conditional moves into real possibility, covering genuine future scenarios that may or may not occur. The second conditional steps away from reality into imagination, describing what would happen in an unlikely or impossible present or future situation. The third conditional goes furthest from reality, looking back at the past to consider how a different choice or event would have changed what actually happened — making it the conditional of hindsight and regret. | ||||
Formula
✔ Positive
If
+
subject
+
verb (present simple)
+
object
+
subject
+
verb (present simple)
+
object
If you press the button, the machine starts.
✖ Negative
If
+
subject
+
don't/doesn't + verb
+
object
+
subject
+
verb (present simple)
+
object
If you don't water the plant, it dies.
? Question
What
+
happens
+
if
+
subject
+
verb (present simple)
What happens if you mix red and blue paint?
Examples
If you heat water to 100°C, it boils.
Scientific fact · General truth
Plants die if they don't get enough water.
Natural consequence · Always true
If you add sugar to tea, it becomes sweet.
Automatic result · Cause and effect
When you exercise regularly, you feel healthier.
Habitual truth · Regular pattern
If babies cry, they need attention.
General fact · Always happens
Ice melts if the temperature rises above 0°C.
Physical law · Unchangeable truth
When to use it
Scientific Rules
Use zero conditional to explain laws of physics, chemistry, and biology. These are universal truths that never change.
"If you freeze water, it becomes ice."
Cooking Instructions
Describe how ingredients behave during cooking or how recipes work. Results are always predictable.
"If you add vinegar to baking soda, it fizzes."
How Things Work
Explain cause-and-effect relationships for machines, devices, or systems. The outcome is automatic.
"If you turn the key, the car engine starts."
Health & Habits
Describe natural consequences of actions or habits that are always true. These are predictable patterns.
"If you get enough sleep, you feel more energetic."
Signal words
if
when
whenever
as soon as
unless
always
never
every time
in case
Common Mistakes
✕
Wrong
If you heat water, it will boil.
✓
Correct
If you heat water, it boils.
Zero conditional uses present simple, not 'will'. Use future only in first/second conditional.
✕
Wrong
If you would eat too much, you get sick.
✓
Correct
If you eat too much, you get sick.
No 'would' in the if-clause for zero conditional. 'Would' belongs to second conditional.
✕
Wrong
When you are exercising regularly, you feel better.
✓
Correct
When you exercise regularly, you feel better.
Use simple present form, not continuous. Zero conditional describes habitual facts, not ongoing actions.
✕
Wrong
If salt is adding to water, it melts.
✓
Correct
If you add salt to water, it dissolves.
Use active voice and correct verb. Passive voice and wrong verb change the meaning.
KEY TAKEAWAYS
What to Remember
- The zero conditional describes general truths and automatic consequences that always happen.
- Use present simple in both the if-clause and the main clause.
- The result is always the same; zero probability of a different outcome.
- Zero conditionals express timeless facts, scientific truths, and universal situations or habits.
- Do not use will or other modals; both clauses must use present simple.