Ensure, Assure, Insure

Updated 19 September, 2022: Barbara of the Bonneville Power Administration in Vancouver, Washington, asked me to write about ensure vs assure vs insure. I am happy to write from the U.S. perspective, and I am hoping my friends across the oceans and borders will enlighten us about any differences.

Here is an illustration with all three words:

I assure you that Morgan did ensure that the company will insure both vehicles.


Here are quick definitions based on my favorite U.S. style guides:

Ensure = make certain.
Insure = protect against financial loss.
Assure = promise, give confidence to.

The noun form of insure is insurance. Outside the insurance industry, some people use insure and ensure interchangeably, but careful writers don’t.


To promote a stronger pace of economic recovery and to help ensure that inflation, over time, is at levels consistent with its mandate, the Committee decided today to expand its holdings of securities. – The New York Times

Obamacare seeks to insure millions more Americans and rein in sky-high medical costs. – The Economist

Many of the IG’s recommendations to assure such actions do not occur in the future have already been acted upon,” he said in the statement. – The Guardian

Ensure vs Insure vs Assure Quiz

Let’s see if we agree which word goes in each blank:

  1. Please _____ that this does not happen again.
  2. You ought to _____ the painting for $24,000.
  3. Please _____ Mrs. Rio that her coat will be delivered to her today.
  4. How can I _____ that the package will arrive by tomorrow?
  5. I _____ you that the figures are correct.

Before I give you my answers, remember my sample sentence with all three words?  Please forget it. It would never be wise to use all three words in one sentence. Doing so would dizzy your readers rather than focusing them on your meaning.

Here are my answers for the blanks above: 1. ensure, 2. insure, 3. assure, 4. ensure, 5. assure.

Please let me know what works in Britain, Australia, Canada, and other lovely places.

Syntax Training

For more articles on confusing words, take a look at our similar words section.

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By Lynn Gaertner-Johnston

Lynn Gaertner-Johnston has helped thousands of employees and managers improve their business writing skills and confidence through her company, Syntax Training. In her corporate training career of more than 20 years, she has worked with executives, engineers, scientists, sales staff, and many other professionals, helping them get their messages across with clarity and tact.

A gifted teacher, Lynn has led writing classes at more than 100 companies and organizations such as MasterCard, Microsoft, Boeing, Nintendo, REI, AARP, Ledcor, and Kaiser Permanente. Near her home in Seattle, Washington, she has taught managerial communications in the MBA programs of the University of Washington and UW Bothell. She has created a communications course, Business Writing That Builds Relationships, and provides the curriculum at no cost to college instructors.

A recognized expert in business writing etiquette, Lynn has been quoted in "The Wall Street Journal," "The Atlantic," "Vanity Fair," and other media.

Lynn sharpened her business writing skills at the University of Notre Dame, where she earned a master's degree in communication, and at Bradley University, with a bachelor's degree in English.

9 comments on “Ensure, Assure, Insure”

  • It would be the same in Canada if linguistic skill was a universal gift.

    I know many people who would argue that both ensure and insure could be used in examples one and four. I do my best to err on the side of kindness.

  • Sudheer, I have written many blog posts about thank-you messages. Please type “thank-you” in the search box at top right, and you will find a list of things I have written, including examples.


  • Thanks! I will share this with my ESL students here in Canada.


  • My compassionate professor thanks a lot for your good obvious explanations of the confused words assure, insure & ensure.
    Of course my kind professor, Jane Straus said,” assure is used to promise or say with confidence. ** it is more about saying than doing.**”
    If may please explain to me the words*** ease & lessen***?
    I kiss your hands,

    iranma4@gmail.com (please send every message to me or [for me(instead of another body)] only about Grammar rules & how I had better do to improve my listening.)

  • My “Merriam-Webster’s Collegiate Dictionary” defines the verb “ease” this way:

    1: to free from something that pains, disquiets, or burdens.
    2: to make less painful.
    3: to lessen the pressure or tension of.

    It defines “lessen” this way: to reduce in size, extent, or degree; decrease.

    I hope that information helps.


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