Conditional sentences (also called "if clauses" or "if sentences") express that one action depends on another. They're essential for discussing possibilities, hypothetical situations, giving advice, expressing regrets, and describing cause-and-effect relationships. Mastering conditionals allows you to express complex ideas about possibility, probability, and hypothetical scenarios.

Overview of Conditional Types

Zero Conditional: General Truths and Facts

Use the zero conditional for things that are always true-scientific facts, general truths, and habitual actions.

Structure: If + present simple, ... present simple

• If you heat water to 100°C, it boils.
• If you mix blue and yellow, you get green.
• If it rains, the ground gets wet.
• If I don't eat breakfast, I feel tired.
• Plants die if they don't get water.

Note: "When" can often replace "if" in zero conditionals: "When you heat water, it boils."

First Conditional: Real/Likely Future Possibilities

Use the first conditional for real possibilities in the future-situations that are likely to happen.

Structure: If + present simple, ... will + base verb

• If it rains tomorrow, we will stay home.
• If she studies hard, she will pass the exam.
• If you call me, I will answer.
• If we leave now, we will catch the train.
• The boss will be angry if we are late.

Variations with other modals:

• If you're tired, you should rest. (advice)
• If it stops raining, we can go outside. (possibility)
• If you finish early, you may leave. (permission)
• If he calls, I might not answer. (uncertain intention)

Second Conditional: Unlikely/Hypothetical Present or Future

Use the second conditional for hypothetical, unlikely, or imaginary situations in the present or future.

Structure: If + past simple, ... would + base verb

• If I won the lottery, I would buy a big house.
• If I had more time, I would learn Japanese.
• If she lived closer, we would meet more often.
• What would you do if you saw a ghost?
• If I were you, I would apologize.

Variations with could and might:

• If I had a car, I could drive you there. (ability)
• If she tried harder, she might succeed. (uncertain result)
• If we left now, we could still make it. (possibility)

Third Conditional: Impossible Past Situations

Use the third conditional to talk about hypothetical situations in the past-things that didn't happen but you're imagining if they had.

Structure: If + past perfect, ... would have + past participle

• If you had studied, you would have passed the exam.
• If I had known about the party, I would have come.
• If we had left earlier, we wouldn't have missed the flight.
• She would have helped if you had asked her.
• If he hadn't broken his leg, he would have won the race.

Expressing regret and criticism:

• If only I had listened to you! (regret)
• If you had been more careful, this wouldn't have happened. (criticism)
• I would have bought it if I had had enough money. (missed opportunity)

Mixed Conditionals

Mixed conditionals combine elements from different conditional types, usually to show how a past event affects the present, or how a general truth relates to the past.

Type 1: Past condition → Present result

If + past perfect, ... would + base verb

• If I had studied medicine, I would be a doctor now.
• If she had accepted the job, she would be living in Paris.
• If we hadn't moved, we would still live in London.

Type 2: Present condition → Past result

If + past simple, ... would have + past participle

• If I were taller, I would have played basketball in school.
• If she didn't have allergies, she would have eaten the cake.
• If he weren't so shy, he would have asked her out.

Unless, As Long As, Provided That

Other words can introduce conditional clauses:

• Unless = if not: "Unless you hurry, you'll miss the bus." (= If you don't hurry...)
• As long as / So long as = only if: "You can borrow my car as long as you're careful."
• Provided that / Providing = only if: "I'll help you provided that you pay me."
• On condition that = only if (formal): "She agreed on condition that we keep it secret."
• In case = because something might happen: "Take an umbrella in case it rains."

Word Order: Can If Clauses Come Second?

Yes! The if-clause can come before or after the main clause. When it comes first, use a comma. When it comes second, no comma is needed.

• If it rains, we will stay home. (comma needed)
• We will stay home if it rains. (no comma)
• If I were you, I would accept. (comma needed)
• I would accept if I were you. (no comma)

Common Mistakes to Avoid

• "If I will see him" → CORRECT: "If I see him" (don't use "will" in the if-clause for first conditional)
• "If I would have known" → CORRECT: "If I had known" (don't use "would" in the if-clause)
• "If I was you" → BETTER: "If I were you" (use "were" for hypothetical with "you")
• "Unless you won't hurry" → CORRECT: "Unless you hurry" (unless = if not, don't double negate)
• Mixing tenses incorrectly: "If I won the lottery, I will buy" → CORRECT: "...I would buy"

Quick Reference: Choosing the Right Conditional

Frequently Asked Questions