ESEN
Which one to use?Intermediateconjuncionconjuncion
WhenvsIf
"When" is for certain future events; "if" is for uncertain or hypothetical ones.
Side-by-side comparison
When
conjuncion"When" is used when you are certain something will happen; it is just a matter of when. It expresses certainty about the future event.
Call me when you arrive. I will be waiting.
When I retire, I want to travel the world.
She cried when she heard the good news.
If
conjuncion"If" is used when the occurrence is uncertain or conditional; it may or may not happen. It expresses doubt or dependence on a condition.
Call me if you need anything. I am here.
If it rains tomorrow, we will cancel the picnic.
What would you do if you won the lottery?
Common mistake
- •"I will call you if you arrive" implies doubt that the person will arrive at all; "I will call you when you arrive" assumes they will.
- •Spanish "cuando" + subjunctive maps to English "when + simple present", it does not map to "if," which is why the choice feels less obvious to Spanish speakers.
Trick to remember it
- •Key question: is it certain to happen? Yes = "when" (certainty, matter of time); possible but uncertain = "if" (doubt).
- •"When I graduate" = I will graduate (just a matter of time); "If I graduate" = I'm not sure I will.
Quick rule
- •When = certain event (matter of time).
- •If = uncertain event (matter of possibility).
Did you know?
One of the most confusing points of English for Spanish speakers is that after WHEN and IF introducing the future, English uses SIMPLE PRESENT, never future tense. "When I ARRIVE" (correct) vs "when I WILL ARRIVE" (wrong). In Spanish, we use the future subjunctive: "cuando LLEGUE", and this subjunctive form feels "future," which leads to trying to use the future in English. But English uses the present as a certainty marker in the temporal clause: the future is already in the main clause ("I WILL call you"), so the conditional/temporal clause goes in the present.
Practise what you learned
Exercise 1 · Pick the right one
_____ I get home, I'll call you. I should be back around seven.
Exercise 2 · Pick the right one
_____ it rains tomorrow, we'll cancel the barbecue.
Exercise 3 · Form the word
Related word pairs
ByvsUntil
"By" indicates a deadline (no later than); "until" indicates continuous duration up to a point.
SincevsFor
"Since" marks the specific point when something started; "for" indicates how long something has lasted.
UnlessvsIf
"Unless" means "if not" or "except if"; "if" is the neutral condition that can be positive or negative.
AvsAn
'A' is used before consonant sounds; 'an' is used before vowel sounds.
Bryan López
Founder of SpeakUP Academy