Conditional sentences let you talk about possibilities, causes and effects, hypothetical situations, and imaginary pasts. The five conditional types cover everything from scientific facts to regret and speculation. Mastering them is one of the highest-value grammar investments for IELTS, Cambridge exams and everyday fluency.
Zero Conditional — General Truths
Form: If/When + present simple → present simple. Used for facts always true. If you heat water to 100°C, it boils.
First Conditional — Realistic Future
Form: If + present simple → will + base verb. Used for probable or possible future events. If it rains tomorrow, we will cancel. Never use will in the if-clause.
Second Conditional — Hypothetical Present/Future
Form: If + past simple → would + base verb. Used for imaginary or unlikely situations and advice with If I were you… If I won the lottery, I would travel the world.
Third Conditional — Impossible Past
Form: If + past perfect → would have + past participle. Used for things that did not happen. If she had applied earlier, she would have got the job. Never use would have in the if-clause.
Mixed Conditionals
Mixed conditionals combine elements across time: a past cause with a present result, or a present state with a past consequence. If I had taken that job (past perfect), I would be rich now (would + base).
Practice Exercises
For full explanations and tables, read the blog article: English Conditional Sentences: The Complete Guide.
Practice What You've Learned
LexFizz has 30 free interactive exercises — no sign-up needed.
Browse All Exercises →
Explore other grammar topics: All Grammar TopicsModal VerbsPast TensesReported Speech
Frequently Asked Questions
How many conditional types are there in English?
There are five main conditional types: Zero Conditional (general truths); First Conditional (realistic future); Second Conditional (hypothetical present/future); Third Conditional (impossible past); Mixed Conditional (combining time frames). Each uses a different combination of tenses in the if-clause and main clause, and each expresses a different degree of probability or reality.
What is the main difference between first and second conditional?
The first conditional (If + present simple, will + base) describes a realistic, probable future situation: If I study hard, I will pass. The second conditional (If + past simple, would + base) describes an imaginary, unlikely or impossible present/future situation: If I were a doctor, I would work for free. The key distinction is probability — first conditional events could realistically happen; second conditional events are hypothetical.
Why can't I use 'will' after 'if' in the first conditional?
English grammar requires the present simple (not will) in the if-clause because the if-clause is a time/condition clause, not a future prediction. The rule mirrors time clauses (when, as soon as, before, after): If it rains (NOT If it will rain), we will cancel. The will belongs only in the main clause where the result is expressed.
What is the third conditional used for?
The third conditional (If + past perfect, would have + past participle) talks about imaginary situations in the past — things that did not happen: If she had studied harder, she would have passed. It is used to express regret (If only I had known), criticism (If you had listened, this would not have happened) or speculation about different past outcomes.
What are mixed conditionals and when should I use them?
Mixed conditionals combine elements from different conditional types to describe a past condition with a present result (or vice versa). Type 1: If I had taken that job (past perfect — past condition), I would be rich now (would + base — present result). Type 2: If she were more organised (past simple — present characteristic), she would have finished by now (would have + participle — past consequence).
Can I put the if-clause second in a conditional sentence?
Yes. The if-clause can come before or after the main clause. When it comes first, add a comma: If it rains, we will cancel. When the main clause comes first, no comma is needed: We will cancel if it rains. Both are equally grammatical. Front-placing the if-clause is often used for emphasis or when introducing a new topic in writing.
What alternatives to 'if' can I use in conditional sentences?
Common alternatives: 'unless' (= if not): Unless you hurry, you'll miss the train; 'provided that / as long as' (stricter condition): You can borrow it as long as you return it; 'supposing / suppose': Supposing you won, what would you do?; 'even if': Even if it rains, we'll go; 'otherwise' (in the main clause): Hurry up; otherwise, we'll be late.
How do conditionals help in IELTS Writing Task 2?
Using all three main conditional types demonstrates grammatical range, which is assessed in the Grammatical Range and Accuracy criterion. Example: First: If governments invest in education, youth unemployment will fall. Second: If people consumed less meat, greenhouse gas emissions would decrease significantly. Third: If stricter regulations had been introduced earlier, the crisis would not have escalated. This variety of structures strongly signals a Band 7+ writer.
Why is 'were' used instead of 'was' in the second conditional?
In the second conditional, 'were' is used for all persons in formal and written English: If I were you, If he were taller, If she were here. This is the subjunctive mood, which signals a hypothetical or counterfactual situation. In informal speech, 'was' is widely used and accepted (If I was you), but 'were' is expected in IELTS and Cambridge exams. The phrase 'If I were you' is a fixed expression always using 'were'.
What is the zero conditional and how does it differ from the first?
The zero conditional (If/When + present simple, present simple) expresses universal truths and facts that are always or generally true: If water reaches 100 degrees, it boils. If you exercise regularly, you feel better. Unlike the first conditional, which describes a probable future event, the zero conditional describes something that is always true whenever the condition is met. 'When' and 'if' are interchangeable in zero conditionals because the outcome is certain.