🔀 Conditional Sentences: Zero to Third

If this, then that — four patterns for different levels of reality

B1 12 min read 5 sections

Zero Conditional — General Truths

The Zero Conditional describes things that are always true — scientific facts, general rules, and automatic results. Both clauses use the Present Simple.

If-clauseResult clauseFull sentence
If you heat water to 100°C,it boils.If you heat water to 100°C, it boils.
If you mix red and blue,you get purple.If you mix red and blue, you get purple.
If I eat too much,I feel sick.If I eat too much, I feel sick.
If it rains,the ground gets wet.If it rains, the ground gets wet.
Tip: In Zero Conditional, "if" can be replaced by "when" with no change in meaning: "When you heat water to 100°C, it boils" = "If you heat water to 100°C, it boils." Both are always true.

First Conditional — Real / Likely Future

The First Conditional describes realistic, possible future situations. The if-clause uses Present Simple, and the result clause uses "will + base verb."

If-clause (Present Simple)Result (will + verb)Situation
If it rains tomorrow,I will stay home.Real possibility
If you study hard,you will pass the exam.Likely outcome
If she calls,I will tell her.Possible event
If we don't hurry,we will miss the train.Warning
Tip: NEVER use "will" in the if-clause: "If it will rain" is WRONG. Always: "If it rains, I will stay home." The if-clause uses Present Simple even though it refers to the future. This is a very common error.

Second Conditional — Unreal / Hypothetical Present

The Second Conditional describes imaginary or unlikely situations in the present or future. The if-clause uses Past Simple, and the result uses "would + base verb." The past tense here does NOT refer to the past — it signals unreality.

If-clause (Past Simple)Result (would + verb)Situation
If I had a million dollars,I would travel the world.Imaginary (I don't have it)
If I spoke perfect English,I would work in London.Hypothetical (I don't yet)
If she were here,she would know what to do.Unreal (she's not here)
If I were you,I would accept the offer.Advice (I'm not you)
Tip: Formal/traditional grammar uses "were" for ALL persons with "to be": "If I were...", "If he were...", "If she were..." This is called the subjunctive. In casual speech, "If I was..." is increasingly common and accepted, but "If I were you..." is always the standard phrase for giving advice.

Third Conditional — Unreal Past / Regrets

The Third Conditional describes imaginary situations in the past — things that didn't happen. It's used for regrets, missed opportunities, and alternative histories. The if-clause uses Past Perfect, and the result uses "would have + past participle."

If-clause (Past Perfect)Result (would have + past part.)Reality
If I had studied harder,I would have passed the exam.I didn't study → I failed.
If she had left earlier,she would have caught the train.She left late → she missed it.
If they had known,they would have helped.They didn't know → they didn't help.
If it hadn't rained,we would have gone to the beach.It rained → we didn't go.
If I had known you were coming, I would have baked a cake.Wenn ich gewusst hätte, dass du kommst, hätte ich einen Kuchen gebacken.

Mixed Conditionals & Common Errors

Mixed conditionals combine elements from different types — typically a third conditional if-clause with a second conditional result, or vice versa:

PatternExampleMeaning
3rd if + 2nd resultIf I had studied medicine, I would be a doctor now.Past cause → present result
2nd if + 3rd resultIf I were braver, I would have asked her out.Permanent trait → past consequence
Tip: The #1 conditional error: using "would" in the if-clause. "If I would have known" is WRONG — say "If I had known." "If I would be rich" is WRONG — say "If I were rich." The "would" always goes in the RESULT clause, never the if-clause.
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