What is the Zero Conditional?
The zero conditional is used to talk about things that are always true — scientific facts, general truths, and situations where one thing always causes another. It is not about a specific moment in time, but about what happens in general.
IF clause: if + present simple
Main clause: present simple
Both clauses use the present simple. The word when can often replace if with no change in meaning.
Examples
If you heat water to 100°C, it boils. (scientific fact)
If it rains, the ground gets wet. (general truth)
Plants die if they don't get enough water. (natural law)
If you mix red and blue, you get purple. (always true)
When I'm tired, I make mistakes. (personal truth)
Zero vs First Conditional
The zero conditional describes what always happens. The first conditional describes what will probably happen in a specific future situation.
Zero: If you touch fire, it burns you. (always true)
First: If you touch that fire, you will burn yourself. (specific warning)
💡 Tip: In zero conditional sentences, if and when are interchangeable.
If you freeze water, it becomes ice. = When you freeze water, it becomes ice.