How to Use Ensure, Insure, and Assure (Word Choice, Examples)

First published on August 16, 2023 by Dalia Y.|Last revised on October 28, 2025

Ensure means "to make something certain to happen". Assure means "to tell someone confidently that something is true". Insure means "to guarantee against loss or harm".

Writing Tips

How to Use Ensure, Insure, and Assure (Word Choice, Examples)

Ensure, insure, and assure: what's the difference?

Though they sound similar and are closely related in meaning, ensure, insure, and assure have distinct meanings and uses in English. Understanding the difference is crucial for clear communication.

Ensure (verb) — to make something certain to happen; to make sure or certain of something.
Insure (verb) — to guarantee or protect against loss or harm, especially financially; to provide or obtain insurance coverage.
Assure (verb) — to tell someone confidently that something is true; to inspire confidence or reassure someone.

Definitions and usage

Ensure (verb)

To make something certain to happen; to make sure or certain of something. This is a general term used for making something sure or safe without a financial connotation.

• Please ensure that all doors are locked before leaving the building.

• The chef took extra care to ensure that each dish was prepared to perfection.

• The company implemented strict security measures to ensure the safety of its employees.

• Double-check your work to ensure that there are no errors before submitting the report.

• The project manager worked tirelessly to ensure that the project was completed on time.

Insure (verb)

To guarantee or protect against loss or harm, especially financially; to provide or obtain insurance coverage. This word relates to things of a financial nature, such as insurance policies.

• He decided to insure his new car against potential accidents and damages.

• The business owner knew the importance of insuring the company's assets to safeguard against unexpected losses.

• She wanted to insure her valuable art collection to protect it from theft or damage.

• The insurance company offered a policy that would insure the traveler's belongings during their vacation.

• It's wise to insure your home against natural disasters like floods and earthquakes.

Assure (verb)

To tell someone confidently that something is true; to inspire confidence or reassure someone. This word is about communicating confidence to another person, not about making an outcome certain.

• She assured her friend that she would be there to support her during the difficult times.

• The company's CEO personally assured the employees that their jobs were secure despite the restructuring.

• The doctor assured the patient that the procedure was safe and well-tested.

• The teacher assured the students that there would be no pop quizzes that week.

• He assured his parents that he would take his studies seriously and improve his grades.

Pro tip! Remember: Assure is for people (telling someone confidently), ensure is for outcomes (making certain something happens), and insure is for financial protection (insurance). A helpful memory aid: you assure a person, ensure an event, and insure against risk.

Ensure and insure are frequently confused with each other, since both words have to do with making a guarantee or making certain of something. The difference is that to insure relates more to things of a financial nature, such as insurance. To ensure is more broadly applicable and just means to make sure or certain of something.

To assure is to tell someone something with confidence so as to reassure or convince them of that thing (usually so that they don't worry about it). In fact, assure is synonymous with reassure, or words like convince, persuade, and so on. Assure is not quite about making certain something will happen (which is to ensure), but to inspire confidence in another person of something.

Synonyms & nearby words

Synonyms for ensure

confirm secure guarantee verify check certify make sure make certain see to it set the seal on

Synonyms for insure

underwrite guarantee cover assure safeguard warranted hedge shield protect insulate

Synonyms for assure

reassure convince satisfy persuade guarantee pledge to attest to promise to

Word origins

Ensure: Late 14c., from Anglo-French enseurer, from en- "make" + Old French seur "sure"; probably influenced by Old French asseurer "assure." Related: Ensured; ensures; ensuring.

Assure: Late 14c., "reassure, give confidence to; make secure or safe, protect; bind by a pledge, give a promise or pledge (to do something)," from Old French asseurer "to reassure, calm, protect, to render sure", from Latin *assecurar.

Insure: Mid-15c., insuren, spelling variant of ensuren "to assure, give formal assurance" (late 14c.), also "make secure, make safe" (c. 1400).

—Online Etymology Dictionary

Practice quiz: Ensure, insure, or assure?

Question 1 of 5

I want to ______ that you are comfortable during your stay.

assure
ensure
insure

Please ______ that the door is locked before you leave.

assure
ensure
insure

You should ______ your car against theft.

assure
ensure
insure

The teacher tried to ______ the students that the test would be easy.

assure
ensure
insure

I want to ______ that this will not happen again.

assure
ensure
insure

FAQs

What does the word "assure" mean? +

Assure means to say confidently that something is true, usually to a person. It's used when telling someone something to inspire confidence or reassure them, similar to "convince."

When is "ensure" the correct word? +

Use ensure to make certain an outcome will happen or to make sure something is certain. It is a general term used for making something sure or safe without a financial meaning.

How is "insure" different from "ensure"? +

Insure means to guarantee or protect against loss or harm, especially financially. It is used for providing or obtaining insurance coverage for things like cars or property against potential loss. Ensure, on the other hand, is broader and doesn't involve financial protection.

Can I use "assure" for an outcome? +

No, assure is used when confidently telling something to a person. Using assure for making an outcome certain is incorrect; ensure is the word for that.

Does "ensure" imply financial protection? +

No, ensure does not imply financial protection against loss; that is the meaning of insure. Ensure simply means to make sure or certain of something without the financial connotation.

Are ensure, assure, and insure interchangeable? +

No, they have distinct meanings and are not interchangeable. Ensure means to make something certain to happen. Assure means to tell someone confidently that something is true. Insure means to guarantee against loss or harm, especially financially.