What is the difference between 'insure' and 'ensure'?

These days, advertisements for insurance are hard to avoid.

On billboards, television, and magazines, it seems like everywhere you look someone is urging you to insure your car, your home, even your vacation.

But when it comes to everyday English speech, another verb, ensure, has a broader and more common usage.

What exactly is the difference between ensure and insure? And what about assure? If these words give you pause, rest assured, you’re not alone.

Insure, ensure, and assure are common words that are easy to confuse. All three have similar meanings related to the idea of making something safe or secure.

To make matters worse, insure and ensure also sound alike. How can you tell which word to use in your writing?

In this article, we’ll cover the key differences between insure, ensure, and assure, with examples of each.

We’ll analyze practice sentences that show how to use insure, ensure, and assure in a sentence. We’ll also discuss some helpful tools, tips, and strategies to ensure correct usage of these words.

We assure you, confusion about insure vs. ensure is very common! Think of this article as your insurance policy against making a mistake with these tricky words.

Insure vs. Ensure: Can You Hear the Difference?

Insure and ensure are near homophones. Homophones are words that sound alike but have different spellings and meanings.

What makes insure and ensure so tricky is that not only are they similar in sound, but also they are similar in meaning. In fact, they are so similar that in some cases they can be used interchangeably!

Complicating matters further, the related word assure overlaps in some meanings with both insure and ensure.

The good news? There are clear rules of thumb that can help you choose correctly between insure, ensure, and assure in most contexts.

Let’s start with these rules of common usage, before tackling the more ambiguous cases.

What Is the Difference? Insure vs. Ensure vs. Assure

The definitions of insure, ensure, and assure are quite similar.

Broadly speaking, each word means “to make sure of something.” But there are important differences in how each word is used in a sentence.

The general rules for insure vs. ensure vs. assure are as follows:

• Insure: to take out an insurance policy (on a car, house, etc.)

• Ensure: to make sure or guarantee that something happens

• Assure: to convince someone that something is true

As you can see, each word has a specific usage and a slightly different meaning. Most English speakers would consider it grammatically incorrect to use these words interchangeably.

Follow this rule of thumb for how to use insure, ensure, and assure in a sentence:

• You insure a car

• You ensure success

• You assure a person

Another helpful hint is to put each word into its noun form. This can help you see the differences more clearly and figure out which word you want.

• Insurance: a contract for coverage that protects you financially

• Ensurance (obsolete word): the act of ensuring

• Assurance: something that inspires confidence

Let’s take a closer look at the definitions of assure, ensure, and insure. We’ve included a few examples so you can see how to use each word in a sentence.

What Does "Insure" Mean?

Insure means to take out an insurance policy. Yep, those insurance policies—the ones that seem to be plastered everywhere in annoying advertisements.

Insure is the narrowest of the three words in question. Luckily for us, that keeps the rule simple: use insure when you need financial insurance.

To insure is to arrange for financial compensation against the loss of something. You buy insurance to protect yourself against risk.

You can insure your health, your convertible, your summer home, or even your life. For example:

• Mark and Mary want to insure their home against hurricane damage.

• Even if you are a renter, it’s a good idea to insure your apartment against theft and natural disasters.

• Andi and Alexis got insured after they spoke to their local broker.

As you can see, most uses of insure relate specifically to the insurance industry. Use the word “insure” when you want an official and specified protection.

What Does "Ensure" Mean?

Is ensure a real word? Yes! In fact, ensure is much more versatile than insure, and can be used in a wide range of contexts.

Ensure means “to make sure, certain, or safe.” You ensure that something will happen by taking extra efforts and precautions.

A good rule of thumb: if you’re trying to say “make sure,” ensure is the correct word to use.

Here are examples of how to use ensure in a sentence:

• These communication strategies will ensure a productive team meeting.

• Stretching thoroughly is the best way to ensure your safety when exercising.

• The food truck and live band at the party ensured that a good time was had by all.

As you can see, ensure isn’t always about finances. It can apply to a wide range of outcomes, both literal and metaphorical.

This makes ensure the most versatile word of these three commonly confused words.

If you want to guarantee something and you’re not sure which word to choose between insure, ensure, and assure, chances are ensure is the right answer.

What Does "Assure" Mean?

Assure also carries the basic meaning of “to make sure or certain,” but it functions differently. Generally speaking, you assure a person.

To assure someone means to give them confidence or increase their certainty. It is a synonym of “reassure.”

Let’s see some examples of assure used in a sentence:

• We assure you, this offer is our best deal of the season.

• They assured Max that they were doing everything they could to find his missing luggage.

• I felt nervous about the procedure, but my doctor assured me that everything would be fine.

Notice how in each example, assure always relates to a person. That person is the one who is made to feel more sure or certain.

This usage differs from insure and ensure, which don’t relate to a person’s feelings.

Shared Meanings of Insure, Ensure, and Assure

Assure, ensure, and insure ultimately derive from the same Latin word, securus, meaning “secure, safe, untroubled, free from care.”

This is the same root that gives us the English adjective “sure.” Later, the common ancestor enseurer in Anglo-French added the prefix en- “make,” hence “to make sure.”

As with many words that share ancestors, the meanings of assure, ensure, and insure can overlap.

In fact, for hundreds of years, insure and ensure were simply spelling variants, with no difference in meaning.

The specific commercial sense of insure as “to make safe against loss by payment of premiums" did not arise until the mid-17th century; prior to this, assure was the preferred spelling for commercial purposes.

As you can see, these words have a very close history. For centuries, they were essentially the same word!

Are "Insure" and "Ensure" Interchangeable?

Yes and no. It depends on who you ask!

Some style guides like The New York Times and The New Yorker allow the use of insure, rather than ensure, when describing the act of protecting oneself. Effectively, they allow insure and ensure to be used as synonyms.

However, other style guides such as Associated Press and the Chicago Manual of Style adhere to a more strict separation, and use insure only for sentences about financial protection via insurance policies.

These guides follow the rules we have described in this article.

We insure things that have monetary value (cars, homes, people), while we ensure a broader range of things like outcomes or accountability.

Assure, meanwhile, has the specific meaning of removing doubt from someone’s mind. But there are still some ambiguities.

In Europe, companies sell “life assurance” (with the idea that eventual payment to the heirs of the policy-holder is assured), while American companies sell “life insurance” alongside policies for theft and health coverage.

Insure vs. Ensure vs. Assure: Practice Sentences

Now that’s we’ve learned the rules for insure, ensure, and assure, let’s put them into practice. Choose the correct verb for each sentence, then check your answers below.

1. The car’s safety features __ that passengers are protected.

2. Last month, Naila __ her home from fire, theft, and flood damage.

3. What can we do to __ the best experience for our customers?

4. The sales rep __ me this was the best insurance policy for my needs.

5. An apple a day __ that the doctor will stay away.

Answer Key for Practice Sentences

1. The correct answer to sentence one is ensure. The safety features make certain that passengers are safe.

2. The correct answer to sentence two is insured. Naila took out an insurance policy.

3. We want to guarantee a great customer experience. The word we are looking for here is ensure, in the sense of make sure.

4. The correct answer to sentence four is assured. The sales rep put my mind at ease and gave me confidence in my policy.

5. The correct answer to sentence five is ensures. Eating the apple makes certain that no doctor visit will be needed.

How Can You Always Use "Ensure" and "Insure" Correctly?

Now that we understand the key differences between insure, ensure, and assure, we are better equipped to distinguish between them.

Still, how can we be 100% certain that we’ve used the right word?

A grammar tool such as ProWritingAid’s Homonym Report can be an excellent resource to ensure that you always choose correctly.

The Homonym Report searches your text for homonyms (words which are pronounced and spelled alike, but have different meanings).

It also looks for homophones (words which sound alike, but have different spellings and meanings), and homographs (words which are spelled alike, but can be pronounced differently and have meanings).

These words can be tricky to find when proofreading, especially when dealing with similar words and meanings like insure, ensure, and assure.

ProWritingAid highlights any words you might have misspelled or chosen incorrectly, and lets you review them easily at the left side of your screen.

Think of it as a little insurance policy against incorrect usage of ensure, insure, and assure!

We Assure You, There Is a Difference!

Because insure, ensure and assure all have the word “sure” in them, it’s easy to get them mixed up.

But with the grammar rules we’ve covered in this article, plus extra practice and lots of reading, the differences will soon seem obvious to you.

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