What is the First Conditional?
The first conditional is used to talk about real or very likely situations in the future and their probable results. Unlike the zero conditional (general truths), the first conditional refers to specific possible situations.
IF clause (condition): if + present simple
Main clause (result): will / can / may / might + infinitive
The condition and result can appear in either order. When the if clause comes first, use a comma before the main clause.
Positive Sentences
If it rains tomorrow, I will stay at home.
She will miss the bus if she doesn't hurry.
If you study hard, you will pass the exam.
Negative Sentences
If he doesn't apologize, she won't forgive him.
We won't finish on time if we don't start now.
Questions
Will you come to the party if I invite you?
What will you do if you miss the flight?
Variations with Modals
You can replace will with other modals to add nuance:
might – uncertainty: If it's warm, we might go to the beach.
can – possibility: If you finish early, you can leave.
should – advice: If you feel ill, you should see a doctor.
⚠ Common mistake: Do NOT use will in the if clause.
✗ If it will rain, I will stay home.
✓ If it rains, I will stay home.