"Assure" is to tell a person not to worry; "ensure" is to take steps to make something happen.
To tell a person confidently that something is true or there is no cause for worry. Always has a human recipient.
I assure you that the package will arrive before Friday.
She assured her parents that she was safe and would call every week.
He assured the board that the project was on track.
To make certain that something happens by taking the necessary steps. The object is a result or situation, not a person.
Please ensure that all doors are locked before leaving.
We need to ensure the quality of the product before launch.
Steps were taken to ensure the safety of all passengers.
Common mistake
Using "assure" when talking about a situation instead of a person: "assure the quality" is incorrect — you "ensure the quality". "Assure" always targets a person ("assure you", "assure them"). "Ensure" is followed by a situation or result ("ensure that", "ensure the safety"). Note: "insure" (to take out an insurance policy) is different from both.
Trick to remember it
Assure = tell a PERSON (human target). Ensure = make certain a RESULT happens (outcome target). "Assure" shares a root with "reassure" (calm someone down). If the target is a person who needs peace of mind: assure. If the target is a result or process: ensure.
Quick rule
Assure + person (you tell them not to worry). Ensure + result/situation (you take steps to make it happen). Insure = take out an insurance policy.
Did you know?
All three words (assure, ensure, insure) come from the same Latin root "securus" (safe, without worry). English gradually differentiated them: assure for people, ensure for outcomes, insure for financial risk. In British English, "insure" and "ensure" are sometimes used interchangeably.
Exercise 1 · Pick the right one
The manager _____ the team that their jobs were not at risk despite the restructuring.
Exercise 2 · Pick the right one
Please _____ that the report is submitted before the 5 p.m. deadline.
Exercise 3 · Form the word
Assure + person (you tell them not to worry). Ensure + result/situation (you take steps to make it happen). Insure = take out an insurance policy.
Using "assure" when talking about a situation instead of a person: "assure the quality" is incorrect — you "ensure the quality". "Assure" always targets a person ("assure you", "assure them"). "Ensure" is followed by a situation or result ("ensure that", "ensure the safety"). Note: "insure" (to take out an insurance policy) is different from both.
Assure = tell a PERSON (human target). Ensure = make certain a RESULT happens (outcome target). "Assure" shares a root with "reassure" (calm someone down). If the target is a person who needs peace of mind: assure. If the target is a result or process: ensure.
Bryan López
Founder of SpeakUP Academy