Zero and Mixed Conditionals: The Two Nobody Teaches

Most courses teach three conditionals and stop. But the numbered three don't cover everything English actually does with if — two important patterns sit outside the list.

Zero conditional: always true

If + present simple, present simple.

Not a prediction and not a hypothesis — a rule about how the world works.

• If you heat water to 100°C, it boils.
• If I don't sleep, I get headaches.
• If a customer complains, we refund them.

The giveaway is that you can replace if with when and lose almost nothing: When you heat water, it boils. That swap never works with the other conditionals — "when I won the lottery, I'd buy a house" is nonsense.

Zero conditional is the one that shows up in workplace English constantly — policies, processes, technical documentation. If the build fails, the pipeline stops. It is the grammar of how things work.

Against the first conditional

• If it rains, the ground gets wet. (zero — always, a fact)
• If it rains, I**'ll take** an umbrella. (first — this specific occasion)

Zero describes a general truth; first predicts one future event.

Mixed conditionals: two different times

The third conditional keeps both halves in the past:

• If I had studied, I would have passed. (past condition → past result)

But often a past condition has a result now:

Past condition → present result

If + past perfect, would + base verb.

• If I had taken that job, I would be in Berlin now.
• If she hadn't missed the flight, she would be here.
• If we had booked earlier, we wouldn't be on the waiting list.

The regret is in the past; the consequence is sitting in front of you.

Present condition → past result

The reverse also exists, though it is rarer.

If + past simple, would have + past participle.

• If I were more organised, I wouldn't have missed the deadline.
• If he didn't hate flying, he would have come with us.

Here a permanent trait explains a specific past event.

The five patterns at a glance

Type	If-clause	Main clause	Used for
Zero	present simple	present simple	always true
First	present simple	will + base	likely future
Second	past simple	would + base	unreal present/future
Third	past perfect	would have + participle	unreal past
Mixed	past perfect	would + base	past cause, present result

Two things worth getting right

Never put will in the if-clause. If it will rain is wrong; it is if it rains. The exception is a polite request — If you will wait a moment — where will means "are willing to".

Were, not was, in the second conditional. If I were you is the fixed form, and were is standard for every subject in careful writing: if he were here. You will hear was in speech, but were is what an exam expects.

In conversation

Regrets over coffee

A: If I'd accepted that offer, I'd be living in Berlin now.

B: Would you though? If you were the type to move abroad, you'd have gone years ago.

A: True. If I get another chance, I'll think about it properly.

Three conditionals in four lines — mixed, mixed the other way, then first. Nobody is thinking about the table; the timeline just requires it.

Try it yourself

The quiz below focuses on the if/when test for zero conditional and on choosing the right mixed pattern.