The Zero Conditional
The zero conditional is English's most straightforward conditional form, used to express facts, scientific truths, and automatic results that are always true. Unlike other conditionals that deal with possibilities or hypothetical situations, the zero conditional describes real cause-and-effect relationships that happen every time without exception.
Formed with if + present simple in both clauses, this conditional is called "zero" because there's no uncertainty involved - the result is guaranteed to happen when the condition is met. It's the conditional of certainty, making it perfect for describing natural laws, scientific processes, general truths, and automatic consequences.
What makes the zero conditional special is its reliability and universality. Whether you're explaining how water behaves at different temperatures, describing automatic processes, giving instructions, or stating general facts about life, this conditional form expresses relationships that are always true for everyone, everywhere.
Mastering the zero conditional gives you a powerful tool for explaining how the world works, sharing knowledge, and expressing certainties with confidence and clarity.
Formation
Structure
If + present simple, present simple
Both clauses use present simple because we're describing facts that are always true
Examples:
- If you heat water, it boils.
- If it rains, the ground gets wet.
- If you press this button, the machine starts.
- If I eat too much, I feel sick.
Alternative with 'when':
- When you heat water, it boils.
- When it rains, the ground gets wet.
- When you press this button, the machine starts.
- When I eat too much, I feel sick.
Common Mistakes to Avoid
✗ "If you will heat water, it will boil."
✓ "If you heat water, it boils."
Don't use 'will' in zero conditional - both clauses use present simple
✗ "If it would rain, the ground gets wet."
✓ "If it rains, the ground gets wet."
Avoid 'would' in zero conditional - use present simple throughout
✗ "If you press this button, the machine will starts."
✓ "If you press this button, the machine starts."
Don't mix tenses - keep both clauses in present simple
✗ "If you might be late, call me."
✓ "If you are late, call me."
Use simple present, not modal verbs, in zero conditional
'If' vs 'When' in Zero Conditional
Use 'If' for:
- Conditions that may or may not happen
- Scientific experiments or controlled situations
- Hypothetical but certain results
"If you heat water to 100°C, it boils."
Use 'When' for:
- Regular, repeated occurrences
- Natural cycles and routine events
- Things that definitely happen
"When the sun sets, it gets dark."
Quick Reference Guide
Remember:
- Formation: If + present simple, present simple
- Purpose: Express facts, truths, and automatic results
- Certainty: 100% - the result always happens
- Time: Timeless truths, not specific to past, present, or future
- Alternative: Can often use 'when' instead of 'if'
- No modals: Don't use will, would, might, could, etc.