Form

Formula: If + present simple, will + infinitive
If clause (condition)Main clause (result)
If it rains,I will take an umbrella.
If you study hard,you 'll pass the exam.
If she doesn't hurry,we 'll miss the bus.
If I see him,I will tell him.
Never use will in the if clause: ✓ "If it rains, I will go home." ✗ "If it will rain, I will go home."
Clause order: The result clause can come first (no comma needed): "I will call you if I need help."

Use

The first conditional describes real, possible situations in the future. The speaker believes the condition could genuinely happen.

UseExample
Future possibility If we leave now, we 'll arrive on time.
Warning / threat If you touch that, you 'll regret it!
Promise If you help me, I 'll buy you dinner.
Advice (imperative result) If you feel sick, see a doctor.

Variations in the result clause

The result clause doesn't always need will. Other forms are possible:

Result formExample
will + infinitiveIf it rains, I will stay home.
can + infinitiveIf you finish early, you can leave.
may/might + infinitiveIf she calls, I might go. (less certain)
imperativeIf you're tired, go to bed!

Exercises

Choose the correct first conditional form.

1. If it ___ tomorrow, we'll cancel the picnic.

2. If you don't hurry, we ___ the bus.

3. I'll lend you some money if you ___ me back next week.

4. If she calls me, I ___ you immediately.