The zero conditional in English

Wait, there’s a zero conditional? Most people are familiar with the first, second and third conditionals, but the zero conditional sometimes goes unnoticed. Which is a shame, because it’s a really useful construction and you’re probably using it all the time too. 

The zero conditional refers to things which are real and possible. They also refer to a time which is always or now. We don’t use the zero conditional to imagine things, and we don’t use it to talk about one specific instance. 

How to use indirect speech in English

The structure of the zero conditional

The zero conditional is made of two clauses: the conditional clause and the main or result clause. The structure of a sentence in the zero conditional is: 

Conditional clause	Main / result clause
If + present simple,	present simple.

• If it rains, the ground gets wet. 

We can change the order of the clauses without changing the meaning. If the main clause comes first in the sentence, we don’t need a comma. 

• The ground gets wet if it rains.

We can also replace the word if with when in the zero conditional. Sometimes, because we are talking about things that are always true, when sounds more natural. The clauses can come in either order.  

• When it rains, the ground gets wet. 
• The ground gets wet when it rains.  

The zero conditional for facts

We use the zero conditional to talk about proven facts. 

• If you heat water to 100°C, it boils. 
• When the sun sets, it gets dark. 
• Metal expands if you heat it. 

The zero conditional for things that are always or usually true

Similarly to facts, we also use the zero conditional to talk about things that always or usually happen, or are usually true. 

• If it’s sunny, I eat lunch in the park. 
• When Christine finishes work early, she usually goes to the gym. 
• I never drink alcohol if I have to work the next day. 

The present continuous in the zero conditional

So far, we’ve only seen the present simple used in the zero conditional. It is also possible to use the present continuous. We use the present continuous in the condition clause: 

If + present continuous, present simple

• If the dog’s eating, we don’t touch him. 
• When I’m driving, I don’t use my phone. 
• The baby wakes up if we are making a lot of noise. 

Imperatives with the zero conditional

We often use the zero conditional to tell people what to do, or to give instructions. To do this, we use the structure: If / When + present tense, imperative

An imperative is the base form of the verb used without a subject. 

• When the water is boiling, add the pasta. 
• If you want to go, buy a ticket. 
• Meet me here if we get separated. 

Modal verbs in the zero conditional

We can use modal verbs in the zero conditional. We usually use them in the result clause. Remember, modal verbs must always be followed by another verb. 

• If you are lactose intolerant, you can’t drink milk.
• When you arrive, you must sign in. 
• If you have a coat, you have to leave it in the cloakroom. 
• You shouldn’t smoke if you want to be healthy. 

Unless in the zero conditional

We can use unless instead of if or when in the conditional clause. Unless means if not. 

• I always eat lunch outside unless it rains. (I always eat lunch outside if it doesn’t rain)
• Unless you pass your test, you can’t drive a car. (If you don’t pass your test, you can’t drive a car) 

The zero conditional in the past

Up until now, we’ve only talked about using present tenses with the zero conditional. However, we can also use the zero conditional to talk about the past. In a similar way to the present tense, we use the zero conditional to talk about things that were facts or were habits in the past. The structure is: If / When + past simple, past simple

• When I went on holiday as a child, we always went to the seaside. 
• If it rained, I took the bus to school. 
• I got pocket money if I helped with the housework. 

Have you used the zero conditional in English before?