Zero Conditional (A2)

In this lesson, you will learn how to use the zero conditional to talk about things that are always true or happen every time under certain conditions.

1. What Is the Zero Conditional?

The zero conditional is used to talk about:

things that are always true
scientific facts and general truths
habits and routines
cause-and-effect situations where the result usually or always happens

2. Form and Clause Order

Key idea: In the zero conditional, both the if-clause and the main clause use the present simple.

If + subject + present simple, subject + present simple

For example: “If you heat water, it boils.” The result can also use can/can’t for an ability or usual result (“If I drink coffee late, I can’t sleep”) or an imperative for an instruction (“If the screen freezes, restart the computer”).

You can start with either the if-clause or the main clause.

If the if-clause comes first, put a comma after it.
If the if-clause comes second, do not use a comma.

Examples:

If you heat water to 100°C, it boils.
If I drink coffee late, I cannot sleep.
If it rains, the grass gets wet.

Note: The order of the clauses can change.

Water boils if you heat it to 100°C.
(No comma is needed when the if-clause comes second.)

Negative Forms

Either clause can be negative. Use the normal present-simple negative form: do/does not + base verb.

“If plants don’t get water, they die.” (negative if-clause)
“If I feel tired, I don’t drive.” (negative main clause)
“If she doesn’t sleep enough, she doesn’t feel well.” (both clauses negative)

Question Forms

To ask about a general result or routine, make the main clause a present-simple question. The if-clause stays in the present simple.

“What do you do if you feel tired?”
“Do you go to the gym if you finish work early?”
“If the bus is late, do you walk to work?”

3. Using the Zero Conditional

A. Facts & Scientific Truths

If you mix red and blue, you get purple.
If you freeze water, it becomes ice.

B. Habits & Everyday Routines

If I finish work early, I go to the gym.
If he wakes up late, he misses the bus.

C. Cause and Effect

If you touch fire, you get burned.
If you drop a glass, it breaks.

4. Imperative Results

The result clause can be an imperative when we give an instruction or advice for a general situation:

“If you feel cold, close the window.”
“If the screen freezes, restart the computer.”
“If you feel cold, don’t open the window.” (negative imperative)
“If the light doesn’t turn green, don’t cross the road.” (negative if-clause + imperative)

The if-clause still uses the present simple; the main clause uses the base verb as an imperative.

5. Using 'When' Instead of 'If'

For general truths and routines, when can often replace if. Both mean “every time this happens”:

“If you heat ice, it melts.”
“When you heat ice, it melts.”

Use if when the condition may not apply to everyone. “If you are allergic to nuts, avoid them” is advice for only some people; “When you are allergic to nuts, avoid them” does not have the same meaning.

The zero conditional works the same way in British and American English. In speech, contractions such as don’t and can’t are common; the grammar pattern does not change.

6. Common Mistakes

For a general fact or routine, do not use will in the result clause:

✗ “If it rains, the grass will get wet.” (not for a general truth)
✓ “If it rains, the grass gets wet.”

Using will changes the meaning to a first conditional prediction about a specific future situation:

Zero conditional: “If I drink coffee late, I can’t sleep.” (= my general experience)
First conditional: “If I drink coffee tonight, I won’t sleep.” (= one possible future result)

Do not use will in the if-clause of a zero conditional:

✗ “If it will rain, the grass gets wet.”
✓ “If it rains, the grass gets wet.”

Do not use a comma before an if-clause in second position:

✗ “The grass gets wet, if it rains.”
✓ “The grass gets wet if it rains.”

Quick check

Try one question now

If you ice in the sun, it .

Check your answer when you are ready.

7. Easy Way to Remember

Zero conditional = present simple + present simple = always true

Think: “If this always happens → that always happens.”

For general instructions, the result can also be an imperative: If + present simple, base verb.