WPWord Play
Home›B1›Grammar›Zero & First Conditional
Ch 5

Zero & First Conditional

If + present, + present/will

Zero conditional: general truths

The zero conditional describes facts, scientific truths, and things that are always true when the condition happens.

If + present simple, + present simple
Scientific fact
If you heat water to 100°C, it boils.
General truth
If it rains, the streets get wet.
Habitual result
If I don't sleep enough, I feel terrible.
"When" can replace "if" in the zero conditional because the result is certain: When you heat water, it boils.

First conditional: real possibility

The first conditional describes a real possibility in the future — something that might genuinely happen.

If + present simple, + will + base verb
Future possibility
If it rains tomorrow, I will stay home.
Warning
If you don't hurry, you will miss the bus.
Promise/offer
If you help me, I will help you.
Can/may alternative
If you come early, we can have coffee first.

Clause order: if clause first or second

Both orders are correct — comma rules change

If clause first → comma
If it rains, I will stay home.
If you study, you will pass.
Main clause first → no comma
I will stay home if it rains.
You will pass if you study.

Zero vs first: the key distinction

Zero — always true
If you mix red and blue, you get purple.
always happens
If I'm late, she gets annoyed.
always the result
First — might happen
If I'm late tomorrow, she will get annoyed.
possible future
If it rains, we will cancel the trip.
real possibility

Common mistakes

If it will rain, I will stay home.
→
If it rains, I will stay home.
if clause: present simple (NOT will)
If you will come, call me.
→
If you come, call me.
never "will" in the if-clause
If water boils, it will become steam.
→
If water boils, it becomes steam.
always-true fact → zero conditional (present both sides)
If I study tonight, I pass the test tomorrow.
→
If I study tonight, I will pass the test tomorrow.
one specific future event → first conditional

Your turn

Answer out loud — full sentences

Answer with zero and first conditionals.

1
What happens if you don't sleep enough?
2
What will you do if it rains this weekend?
3
If you pass your next exam, how will you celebrate?
4
Say two facts with If… (If you heat ice…)

Recap

Zero
If + present, + present
If water boils, it becomes steam.
First
If + present, + will + base
If it rains, I will stay home.
Key rule
NEVER "will" in the if clause
If it rains (NOT if it will rain)
Comma
if clause first → comma · main first → no comma
If it rains, I'll stay. / I'll stay if it rains.
Practice now →