Zero Conditional: Facts and Instructions

01Facts: things that are always true

Use the zero conditional for facts, like science or how things work. The result is always the same, every time. Both verbs are in the present simple. Remember the -s with he, she and it.

• If you mix red and blue, you get purple.
• Water boils if you heat it to 212 degrees.
• If you don't water a plant, it dies.
• My laptop shuts down if the battery gets too low.

02Habits: if or when

We also use it for habits and routines. Here if and when are very close in meaning, like "every time." Use when for things that happen often or for sure. Use if for things that may or may not happen.

• When I get home, I take off my shoes.
• If I have time, I walk to work.
• My dad gets upset when his team loses.
• When it's hot, we go to the pool.

03Instructions: if + present, imperative

To give instructions or advice, use an imperative in the result part: call, take, press, don't touch. You see this on signs, at work, in apartment buildings and at the doctor's office.

• If you have a fever, stay home.
• If the light is red, don't cross.
• Press 2 if you want to speak to a nurse.
• If you have questions, ask me.

04Word order and commas

The if part can come first or second. When it comes first, put a comma after it. When it comes second, you don't need a comma. Never use will in the if part.

05Common mistakes