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Which one to use?Intermediateverbverb

AssurevsEnsure

'Assure' means to tell someone with confidence that something is true; 'ensure' means to take steps to make certain something happens.

Side-by-side comparison

Assure
verb

"Assure" is directed at a person: you reassure them and give them certainty about something. "I assure you it's safe" means I promise you it is safe.

  • I can assure you that the data was reviewed by three independent teams before publication.

  • She assured the investors that the project would be completed within the original budget.

  • He called to assure his family that he had arrived safely after the long drive.

Ensure
verb

"Ensure" is directed at an outcome: you guarantee that something happens. There is no person to reassure; there is a situation to secure.

  • Please double-check the report to ensure there are no errors before it goes to the client.

  • The new protocol was designed to ensure patient confidentiality at every stage of treatment.

  • Back up your files regularly to ensure you never lose critical work.

Common mistake

  • •"Please ensure the client that we are on track" is wrong: the client is a person, so you "assure" them.
  • •"Ensure" goes with results and situations: "ensure the quality", "ensure the deadline is met".

Trick to remember it

  • •Are you telling a person something to remove their worry? "Assure".
  • •Are you taking concrete steps to guarantee an outcome? "Ensure".

Quick rule

  • •"Assure" = reassure a person.
  • •"Ensure" = guarantee a result or situation through action.

Did you know?

There is a third word that causes extra confusion in financial contexts: "insure", to protect against risk with an insurance policy ("insure your car", "insure a shipment"). The full distinction: assure = put a person at ease; ensure = guarantee a result; insure = take out a financial policy.

Practise what you learned

Exercise 1 · Pick the right one

I called my mum to _____ her that I had arrived safely. She was very worried.

Exercise 2 · Pick the right one

Double-check the dates to _____ there are no mistakes before you send it.

Exercise 3 · Form the word

Complete: "I _____ you that everything will be fine. There's nothing to worry about." (assure / ensure)

Bryan López

Founder of SpeakUP Academy