A2 Grammar Conditionals

The Zero Conditional in English

The zero conditional describes things that are always true: facts, scientific laws, habits and instructions — If you heat ice, it melts. Both clauses use the present simple, and the result is certain every time the condition is met.

The zero conditional is the simplest of the English conditionals. We use it to talk about situations that are always true — where one thing inevitably follows another. Unlike the first, second and third conditionals, which deal with possible, unreal or past situations, the zero conditional has no element of doubt. If the condition happens, the result always happens.

The defining feature is that both clauses use the present simple. There is no will, no would, and no special verb form — just two present-simple verbs joined by if or when. This makes it an excellent starting point for learners before moving on to the more complex conditionals.

Structure of the Zero Conditional

The pattern is fixed and symmetrical: an if-clause (the condition) and a main clause (the result), both in the present simple.

If-clause (condition) Main clause (result)
If + present simple present simple
If you heat water to 100°C, it boils.
If I drink coffee late, I don't sleep well.

The order of the clauses can be reversed without changing the meaning. When the if-clause comes first, we use a comma; when it comes second, we usually do not.

When We Use the Zero Conditional

The zero conditional covers four main meanings, all involving certainty or general truth.

Use Example
Scientific facts If you mix blue and yellow, you get green.
General truths If people don't eat, they get hungry.
Habits and routines If I have time, I read before bed.
Instructions and rules If the alarm rings, leave the building.

If vs when: In the zero conditional, if and when are almost interchangeable, because the result always follows: If/When you heat ice, it melts. Use when if the condition definitely happens, and if if it only sometimes happens.

Zero Conditional for Instructions

A common and very practical use is giving instructions or stating rules. Here the main clause is often an imperative rather than a statement.

This is why instruction manuals, safety notices and recipes are full of zero conditionals — they describe reliable cause and effect.

Zero Conditional vs First Conditional

Learners often confuse these two. The difference is about certainty. The zero conditional describes what is always true; the first conditional describes one specific, likely future result.

Zero conditional (always true) First conditional (one future possibility)
If it rains, the grass gets wet. If it rains tomorrow, we will stay home.
If you don't water plants, they die. If you don't water that plant, it will die.

Notice that the first conditional uses will in the main clause and points to a single future event, while the zero conditional keeps both verbs in the present simple to express a timeless rule.

Common Mistakes

Practice Exercises

Grammar Quiz

Choose the correct present-simple form in zero conditional sentences.

Cloze Dropdown

Select the right verb to complete each conditional gap.

Complete the Sentence

Type the correct present-simple verb in both clauses.

Matching Pairs

Match conditions with their inevitable results.

Unjumble

Reorder words into correct zero conditional sentences.

Flash Cards

Drill facts, rules and instructions in the zero conditional.

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Explore related grammar topics:

All Grammar Topics Conditionals Mixed Conditionals Present Simple Imperatives

Frequently Asked Questions

What is the zero conditional?
The zero conditional is a sentence pattern used for things that are always true — facts, scientific laws, general truths, habits and instructions. Both clauses use the present simple: If you heat ice, it melts. Unlike other conditionals, there is no doubt: if the condition happens, the result always happens.
How do I form the zero conditional?
Use if + present simple in the condition clause and the present simple in the result clause: If you press this button, the machine stops. You can reverse the clauses without changing the meaning. When the if-clause comes first, add a comma; when it comes second, no comma is needed.
Can I use 'when' instead of 'if' in the zero conditional?
Yes. Because the result always follows, if and when are almost interchangeable: If/When you heat water, it boils. Choose when if the condition definitely occurs, and if if it only sometimes occurs. This near-equivalence is unique to the zero conditional.
What is the difference between the zero and first conditional?
The zero conditional describes what is always true, with both verbs in the present simple: If it rains, the grass gets wet. The first conditional describes one likely future result, using will in the main clause: If it rains tomorrow, we will stay home. The key difference is timeless certainty versus a single future possibility.
Can the zero conditional use an imperative?
Yes. When giving instructions or rules, the result clause is often an imperative: If the alarm rings, leave the building. This is common in manuals, recipes and safety notices, because the zero conditional naturally expresses reliable cause and effect.
Why can't I use 'will' in the zero conditional?
Will points to a specific future event, but the zero conditional expresses a timeless, repeating truth, so it stays in the present simple. Say If you heat ice, it melts, not it will melt. Using will turns the sentence into a first conditional about one future occasion.
What kinds of meaning does the zero conditional express?
It expresses four main meanings: scientific facts (If you mix blue and yellow, you get green), general truths (If people don't eat, they get hungry), habits or routines (If I have time, I read before bed) and instructions or rules (If the alarm rings, leave). All share the idea of certain, repeating cause and effect.
Do I need a comma in the zero conditional?
Use a comma only when the if-clause comes first: If you press the button, it starts. If the main clause comes first, no comma is needed: It starts if you press the button. The comma marks the boundary between condition and result when the order puts the condition up front.
Can the zero conditional be negative?
Yes, either clause can be negative: If you don't water plants, they die; If you heat ice, it doesn't stay solid. Form the negative with don't or doesn't plus the base verb, keeping both clauses in the present simple as usual.
Is the zero conditional easy for beginners?
Yes — it is usually taught first at A2 level because it only requires the present simple in both clauses, with no special verb forms. Mastering it builds a solid foundation before learners move on to the first, second and third conditionals, which add will, would and past forms.