The zero conditional is used to talk about rules, general truths, routines, and facts—things that are always or generally true. It’s one of the most common conditional forms in English and is often used in science, instructions, habits, and cause-and-effect situations.
In this article, you’ll learn what the zero conditional means, when to use it, how to form it, and see real-life examples to help you understand and use it confidently.
What Is the Zero Conditional?
The zero conditional is used to express things that are always true when a certain condition is met. These are facts, general truths, habits, or rules—not possibilities or future predictions. It’s called “zero” because it’s the most basic and certain type of conditional: if A happens, B always happens.
Example:
-
If you heat water to 100°C, it boils.
(= This is always true. It’s a fact.)
When to Use the Zero Conditional
Use the zero conditional when:
-
Talking about scientific or universal facts
If you mix red and blue, you get purple. -
Describing habits and routines
If I skip breakfast, I feel tired. -
Giving instructions, rules, or warnings
If the light turns red, stop immediately. -
Explaining cause-and-effect relationships
If you leave food out, it goes bad.
Zero Conditional Structure
The zero conditional has a simple, regular form:
Form: If + Present Simple, Present Simple
Both the condition and result use the present simple tense.
- If it rains, the streets get wet.
- If you don’t water plants, they die.
You can also reverse the order:
- The streets get wet if it rains.
- Plants die if you don’t water them.
Examples of Zero Conditional Sentences
Here are examples in everyday and academic English:
Science & Facts
- If you heat ice, it melts.
- If you don’t water plants, they die.
- If you mix red and blue, you get purple.
Habits & Routines
- If she walks to work, she listens to music.
- If we eat late, we skip breakfast.
- If I drink coffee at night, I can’t sleep.
Instructions & Warnings
- If the alarm goes off, leave the building.
- If you touch that wire, you get shocked.
- If you press this button, the machine starts.
“If” vs. “When” in Zero Conditionals
In zero conditional sentences, the words “if” and “when” can often be used interchangeably. This is because zero conditionals talk about facts, routines, and things that are always true. Whether you use “if” or “when”, the meaning stays the same — you’re referring to something that always happens in a particular situation.
Examples:
- If you heat metal, it expands.
- When you heat metal, it expands.
Note: Use “if” more often when emphasizing the condition, and “when” when focusing on the timing or routine — but in zero conditionals, both are grammatically correct and commonly used.
