"Safe" = free from danger; "sure" = certain in your mind (mental certainty).
Secure in the sense of being protected, without physical risk or danger.
Is it safe to swim here? I heard there are sometimes jellyfish.
The children are safe at school. Don't worry.
Always wear your seatbelt. It's the safest thing you can do in a car.
Certain in the sense of being convinced, having mental certainty or confidence.
Are you sure you turned off the gas before leaving?
I'm not sure where she lives. You should ask someone else.
Sure! I would love to join you for dinner.
Common mistake
This is one of the most common errors for Spanish speakers because in Spanish "seguro" covers both meanings. In English they are different words: "Are you safe?" (are you in a safe place, without danger?) vs "Are you sure?" (are you convinced, certain?). "I am safe" = I am out of danger. "I am sure" = I am certain about something mentally. Confusing them can completely change the meaning.
Trick to remember it
Safe = physical safety (think "safe zone" or "play it safe" — protection from real dangers). Sure = mental certainty (think "I'm sure about it" — internal conviction). In Spanish you need two phrases: "estar a salvo" (safe) and "estar seguro de algo" (sure). English also needs two different words.
Quick rule
Safe = no physical danger, out of harm. Sure = mentally convinced, certain. In Spanish both translate to "seguro" but in English they are different words.
Did you know?
"Sure" as an informal affirmative response ("Sure!") is a very marked Americanism. British speakers rarely respond "sure" to an invitation — they prefer "of course", "certainly", or "absolutely". Using "sure" with a British speaker will be understood, but it will sound distinctly American. This regional difference shows how common words vary in use by country.
Exercise 1 · Pick the right one
The neighborhood is completely _____ at night. You can walk around without any problems.
Exercise 2 · Pick the right one
Are you _____ you locked the front door? I don't want to go back and check.
Exercise 3 · Form the word
Safe = no physical danger, out of harm. Sure = mentally convinced, certain. In Spanish both translate to "seguro" but in English they are different words.
This is one of the most common errors for Spanish speakers because in Spanish "seguro" covers both meanings. In English they are different words: "Are you safe?" (are you in a safe place, without danger?) vs "Are you sure?" (are you convinced, certain?). "I am safe" = I am out of danger. "I am sure" = I am certain about something mentally. Confusing them can completely change the meaning.
Safe = physical safety (think "safe zone" or "play it safe" — protection from real dangers). Sure = mental certainty (think "I'm sure about it" — internal conviction). In Spanish you need two phrases: "estar a salvo" (safe) and "estar seguro de algo" (sure). English also needs two different words.
Bryan López
Founder of SpeakUP Academy