Insure vs. Assure vs. Ensure: What’s the Difference?

Kim Bussing is a college-level composition and rhetoric instructor. Her writing has appeared in publications such as Reader's Digest and Taste of Home.

Ensure, insure, and assure are three of the most commonly confused verbs in the English language. All three words are derived from the Latin word "securus," meaning "secure," and they have some similarities in their definitions. However, these terms should not be used interchangeably.

How to Use Ensure

Ensure refers to the act of making something certain. When you ensure something, you do what is necessary to make that event or action occurs. For example, studying for a test ensures that you will not fail the test.

How to Use Assure

Assure refers to the act of removing insecurities by guaranteeing that something will happen. The act of assuring is the act of dispelling doubts. In a sentence, assure will generally precede the object that you are assuring, as in, "The mother assured her daughter that the loud thunderstorm would not hurt her."

How to Use Insure

Insure refers to the act of taking out an insurance policy to protect something, such as taking out life insurance or insuring a car. If you insure your car, you will be financially protected if the car is damaged in an accident.

Keep in mind that these rules refer to American English. In British English, “assurance” actually refers to a type of “insurance.”

Examples

• The insurance agent assured them that their new policy would protect their home in case of a flood: In this sentence, an agent responsible for providing financial compensation for properties is able to guarantee that a couple will receive fair payment should anything happen to their home.
• The two speakers met before the conference to ensure their speeches did not overlap: Here, ensure indicates that the two speakers have made sure their speeches are unique so they will not be surprised by any similarities after presenting.
• The professor assured the students that the test would only cover chapter nine, and that to ensure a good grade, they should reread the chapter: After the professor dispelled doubt that the test would cover any additional material, she told them that they could be sure of a good test score if they studied the relevant chapter.
• Despite recent layoffs, the manager assures us that our positions are safe: By assuring her employees, the manager is removing fears about losing their jobs and telling them that they are going to be okay. However, this is different than ensuring the jobs are safe, which would involve actively making certain that the speaker and his or her coworkers will retain their jobs.
• Recent regulatory policies ensure that carbon emissions are decreasing, helping assure those worried about global warming: The act of regulation has made certain that carbon emissions will decrease, while this decrease has helped allay fears among those concerned about the environment.
• Stefanie assured us that Kyle had ensured the company would insure the painting in case of damage: In this sentence, Stefanie is promising that thanks to Kyle making certain that the company did what they said they were going to do, the painting would be financially protected in case something unfortunate happened.

How to Remember the Difference

Pay attention to the first letter of each word. “Assure” starts with the same letter as “alive." You can only assure someone who is alive, because you must be alive to feel doubt or fear in the first place. “Insure” begins with the same letter as “income.” Not having a good insurance policy could impact your income. “Ensure” is a guarantee that something will happen — think of the double “e’s” at the end of "guarantee" to ensure that you’ll remember.

What About Reassure?

Reassure is a combination of the prefix “re” and the word “assure,” and it can be used interchangeably with the latter to mean removing insecurities. However, just because they have the same meaning does not make them perfect substitutes. "Reassure" should be used only in situations of repeated assurance, or when someone reverts to a previously held opinion (e.g. "She was reassured of her original convictions.")