Grammar Assure vs. Ensure vs. Insure |
The Blue Book of Grammar and Punctuation

Assure vs. Ensure vs. Insure

The three words, assure, ensure, and insure, are often confused. All three words share an element of “making an outcome sure.” However, rather than using these words interchangeably, I’d like to point out the unique aspects of each word so that you can use them to communicate your intention clearly.

Assure is to promise or say with confidence. It is more about saying than doing.
Example: I assure you that you’ll be warm enough.

Ensure is to do or have what is necessary for success.
Example: These blankets ensure that you’ll be warm enough.

Insure is to cover with an insurance policy.
Example: I will insure my home with additional fire and flood policies.

Especially in American English, what you insure is a business transaction. What you ensure results from your personal efforts.


Pop Quiz

Choose the correct word in each sentence. Scroll down to view answers.

1. I assure/ensure/insure you that I have been honest about the money I spent.

2. I will assure/ensure/insure my car as required by law.

3. Mauricio saved money from every paycheck to assure/ensure/insure he could buy gifts for his family at the end of the year.

Pop Quiz Answers

1. I assure you that I have been honest about the money I spent.

2. I will insure my car as required by law.

3. Mauricio saved money from every paycheck to ensure he could buy gifts for his family at the end of the year.

If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.

111 responses to “Assure vs. Ensure vs. Insure

  1. Josh says:

    “We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility…”

    I’ve been wondering if the Founders should have written “ensure” there. Of course, it could well be that the distinction between “insure” and “ensure” has changed since the late 18th century.

    • Jane says:

      You’re correct. Today we would use “ensure” in this case. I imagine that you are also correct that the distinction between “insure” and “ensure” came later. Thanks for writing.

      • Mark says:

        insure would also mean secure or protect someone against (a possible contingency. The example would be the following:
        “by appeasing Celia they might insure themselves against further misfortune”

        I believe the founders had it right and there is not distinction made for the passage of time.

        RIP Jane

    • Sylvie says:

      American english doesn’t usually differentiate between insure and ensure like British english does. There are a few other instances of this.

  2. Thomas Hollander says:

    Insure means more than just “issue an insurance policy.” It also means “to make certain especially by taking necessary measures and precautions.”

    It’s in that spirit that the NRA uses the word in their ads.

    • Jane says:

      The second definition of “to make certain” is better to spell “ensure” rather than “insure.”

      • MikeyD says:

        Yes, but as the NRA considers membership as insurance to protect one’s gun ownership, “insure” is the correct term. In this case the “insurance” they offer is political bargaining power and not a traditional monetary policy, but it is insurance none the less.

        • As Jane responded on October 28, 2010, the second definition of “to make certain” is better to spell “ensure” rather than “insure.”

          • Lee says:

            No, it’s not. The way they have used it is perfectly correct. I understand their message much more as to PROTECT rights rather than to make certain of them. I realize both are positive messages, but the first (protect) is much more what they meant.

            • While insure is not wrong, in the absence of an insurance policy, we prefer using ensure to convey “to make secure or certain,” especially where that security or certainty result from your personal efforts (which, in this case could be joining the NRA).

          • Randall says:

            I would say that a person ensures their financial stability by buying insurance. i.e. you insure something tangible e.g. car, house, health, etc.
            You ensure more esoteric things like success through good planning, knowledge, etc.
            Now the tricky part comes into play. Is a Right something tangible like health, or is it esoteric like success. I would argue that it is a tangible thing that would be insured by having an advocate to government.

          • Troy says:

            The distinction between “ensure” and “insure” seems to be one of agency. I can ensure an outcome, but I can use another entity to insure an outcome. I can ensure my gun rights, or I can pay the NRA to insure my gun rights. Make sense? No? Just my two cents…

  3. Jennifer says:

    I am a medical transcriptionist and this was an excellent explanation. Thank you. I have the Blue Book.

  4. Sam Wright says:

    While I agree there are instances when the use of either word is appropriate, there is a subtle distinction between ensure and insure that is not being appreciated in this article. I (and many others) correctly use “insure” to emphasize the active implementation of measures that makes a desired outcome more certain. To tie it strictly to the issuance of an insurance policy leaves its definition remarkably (and incorrectly) narrow.

  5. matthew says:

    I really appreciate the clarity on this. Not knowing the distinctions have always bothered me. BTW- the term “bad” grammar has always bothered me as well. In the spirit of Chomsky’s theory that grammar is innate, I find myself wanting to correct/change the word “bad” to “poor”. Is there any basis to my… pet peeve?

    • We would say that either “bad grammar” or “poor grammar” would be equally acceptable. The Merriam-Webster Dictionary defines “bad” as “failing to reach an acceptable standard: poor.” In this case, the two words seem interchangeable. Your pet peeve is just a matter of personal preference.

  6. Russ says:

    Great explanation. Thanks!

    But why then do we sometimes hear: “… to help ensure…”? It seems the intended meaning of this construct is to make the occcurrence of something ‘more likely’, which seems to negate the meaning of ensure, which is to make it ‘certain’.

    “I will ensure the money is raised” versus “I will help ensure the money is raised”

    • When we hear the phrase “to help ensure,” we take it to mean “to help make sure” or “promote the certainty” of something.

    • Frank says:

      The difference in your example is a simple reference to whether one participant or multiple participants will be doing the “ensuring.”

  7. Sam says:

    I see you’re of the “let’s remove all subtlety and make everything easy” ilk. This mind-set only serves to increase the difficulty of expressing nuanced thoughts and instead favors ideas that are strictly balck or white.

    • One could also argue that the interchangeable use of the words insure and ensure is what removes subtlety. We can, however, understand what you are saying if referencing only Webster’s New Collegiate Dictionary where the word insure carries the meaning “to make certain by taking necessary measures and precautions.” (Webster’s also lists ensure as a synonym.) Other dictionaries we checked do not appear to make this distinction.

    • Mike says:

      It seems to me that the difference between insure and ensure is not really that subtle at all. To ensure something is to take a proactive action to make sure something happens (or doesn’t happen). To insure against something (or to insure something) is to take steps to mitigate the negative effects of that thing happening (e.g. hedging one’s bets). Jane makes this point very well in response to Bryan. I disagree that insure is simply a stronger form of ensure, and I think that by modern standards the NRA got it wrong, and so did the Founders, although of course it may well have been correct in their day.

      • Doug says:

        I think Mike’s interpretation is spot on. ‘Ensure’ has to do with taking active steps to cause something to (or not to) happen. ‘Insure’ is about mitigating the effects of something happening (or not happening). They are two very different concepts, and people using the terms synonymously damages the not-so-subtle distinction.

      • zylstra says:

        Yes, this is the difference!

      • Jon says:

        This is the correct explanation of the difference – all the comments about financial protection are misleading and confusing the point.

        Ensuring is to make certain something doesn’t happen.
        Insuring is about planning for the eventuality that it might.

        Or vice versa.

        The NRA, and many others, are simply mistaken in their use of the word ‘insure’. Their intended message is a recommendation that you act to make certain that your rights are protected. They are not offering an alternative to gun ownership if your rights are removed.

  8. JanetB says:

    I’m a great believer in correct spelling and grammar and it is very helpful, even though I know that the words are all different, to actually have the differences in writing. This means I can make sure when I am proof-reading tutorials that they are correct.
    Thanks very much.

  9. P.H. says:

    Is this another example of differences between American English and British English, such as “grey” v. “gray”, “judgment” v. “judgement”, etc?

    • According to the The American Heritage Dictionary of the English Language, there is even more overlap between assure and insure. In British English, assure can also take on the meaning of “to insure against loss.”

  10. gingerbreadman says:

    Just found this post. I’m currently in a lecture and a colleague thought that there is a grammar error on the presentation: “…please INSURE and obtain a TRACKING number as a safeguard.” He thinks ENSURE should be used in this context. Kindly tell me your take on this. Thanks in advance.

    • If the presenter is literally requesting that the sender add insurance coverage to the shipment, then it is correct as written:
      “Please insure and obtain a tracking number as a safeguard.”

      However, if the intent is simply to make sure that a tracking number is obtained, we prefer the word ensure for clarity; however, insure may also be used.

      • leslie erentreich says:

        I believe that it is quite clear that “insure” is the correct word.

        “Please insure and obtain a tracking number as a safeguard”.

        They are asking for two items that will serve as a safeguard for the item that is to be mailed. We know this because of the use of “and”. The first item is to “insure” the package, as in purchase an insurance policy. The second is to obtain a tracking number.

        If they meant “ensure” then the sentence would be “Please ensure to obtain a tracking number as a safeguard”.

        • As we stated in our earlier response, if the presenter is literally requesting that the sender add insurance coverage to the shipment, then it is correct as written. It is impossible to guess the intent of the original writer, therefore we hesitate to claim that any answer is “quite clear.” If adding insurance is not the intent, a better sentence would be “Please ensure that you obtain a tracking number as a safeguard.”

  11. Matt says:

    Thanks for the info…I have terrible grammar.

  12. Bobbi says:

    Thanks Jane for taking the time to post this. I have always had a difficult time with a lot of the English grammar and this helps a bunch.

  13. John USPO says:

    It seems as though Sam likes to hear himself (or in this instance, SEE himself) argue.
    Anyway, I’m a Federal Probation Officer and have been interchanging the words assure, ensure, and insure for a few months now. I haven’t been able to obtain good clarification until now. Thanks for the info and keep it up!

  14. Shane says:

    I was just writing a letter and wondering if insure and ensure could be different but the same, good reference…

  15. James says:

    I like your definitions because they are simple and clear.

    However the definition of ‘ensure’ – to make sure something will/won’t happen – seems a little restrictive as your example demonstrates. Installing a smoke alarm does not ensure the safety of your family even though the person fitting it assures you that it will. This is why we have insurance.

    I think we can ensure that something is the case but we can say very little about what will happen in the future.

    • Our definition of ensure is reasonably similar to every dictionary definition available: to make sure or certain. But, examined closely, you’re right that there is very little that we can say with certainty about the future. Ensure is perhaps our best human effort to predict a safe future. We do like your two sentences where you use all three words: ensure, assure(s), and insure (insurance).

  16. Jay Tittman says:

    Language changes over time. I confirm what Josh said a few years ago about the use of “insure” in the preamble to the Constitution. I’m up to number 35 in reading The Federalist papers and have already found Hamilton using “insure” (and not once using “ensure”) at least a half-dozen times already, in places where current usage would dictate “ensure”.

  17. susan klee says:

    OK, OK maybe modern usage demands that these words are interchangeable . . .
    I don’t like to be a “strict constructionist” (heaven forfend)! But ya know; It’s kinda *fun* to be able to make fine distinctions, to differentiate among close synonyms, to use the tens of thousands of words in English differently, whenever you can.
    I hate to see some of these distinctions lost, simply because we then lose the interest of using them literally for the fun of it. I feel the same way about lie/lay/lain . . . It’s fun to know the difference between lie/lay/lain and lay/laid/laid. Isn’t it??

    • Ya know, we kinda doubt you’ll be accused of being a strict constructionist! Seriously, we’re glad that you and many of our weekly E-Newsletter readers and blog writers join us in finding grammar fun. We do enjoy fine distinctions and that’s why the blog titled, “Assure vs Ensure vs Insure” makes distinctions between these words (even though the distinctions are not always quite so clearly defined). And, indeed, it is not only fun but good grammar to know the lie/lay rules (see the chart on p. 3 of Spelling, Vocabulary, and Confusing Words) which have not changed through modern usage.

  18. Bryan says:

    I assure you that I will insure my car in order to help ensure my safety.

    • We understand what you are trying to do with your sentence, Bryan. Unfortunately, insuring your car does not necessarily ensure your safety. It does help ensure that costs for damages to property and persons are covered.

  19. B says:

    Words like everything else evolve over time. The definition of a word is in the context and usage. Meaning that the way that a word is used in a sentence can change the meaning of the word over time. Or add an additional definition to the word.

  20. KoloradoKim says:

    This was a great help for me as I needed to put the correct term in my resume. Thank you for the quick, accurate explanation since I haven’t had a chance to dig the book out from my recent move.

  21. Andrea says:

    Which would be the correct grammar?

    Insure the tradition of excellence.
    Ensure the tradition of excellence.

    • Our blog Assure vs. Ensure vs. Insure makes the distinction that the definition of ensure is “to make sure something will or won’t happen,” whereas insure means “to issue an insurance policy.” Therefore, “Ensure the tradition of excellence” is a better choice.

  22. Denay says:

    Which would be proper/correct grammar?

    1. please assure these are updated in the minutes
    2. please ensure these are updated in the minutes


  23. Lee says:

    I feel like they meant insure in the manner of protection, as in PROTECT your rights. It’s correct as is.

    • While insure is not wrong, in the absence of an insurance policy, we prefer using the word ensure to convey “to make secure or certain,” especially where that security or certainty result from your personal efforts (which, in this case could be joining the NRA).

      • Brian says:

        While “ensure” would be the proper word in the context, the NRA actually does provide firearms-related insurance to its members.

  24. Barbara Saunders says:

    Maybe they mean, give us money to “insure” your gun rights!

  25. vYzion says:

    “Especially in American English, what you insure is a business transaction.”

    You don’t “insure” the transaction itself. You “insure” some product or service involved in a business transaction (i.e., “insuring” is itself a business transaction).

    Can’t wait to read the book!!

  26. Lily says:

    Take a look at the New York Times headline this morning (Aug. 6th, 2013): “Obama to Urge U.S. to Keep Ensuring Mortgages”.. Should it not be “Insuring”?

  27. Randy says:

    I always like to say you assure people/persons/perhaps organizations about something, while you ensure that a certain result is going to happen. In most cases ensure is going to be the right word

  28. Susan says:

    I am afraid that on this one issue, I must beg to disagree. In the UK, people distinguish between these words in their pronunciation and in their writing. This is assuring for it ensures a level of insurance against the confusions that are more common regarding these words in the U.S.

    The confusions in the United States are largely due to the fact that we do not differentiate between insure and ensure in our speech with the common pronunciation being “in-sure.” I expect that in due time, ensure will become unused in American writing as the writing reflects what is said. These sorts of changes in language are always occurring . . . hence the great changes from Old English to Middle English to Renaissance English to contemporary British English and contemporary American English.

    • Thank you for the information regarding the use of the English language in the UK. Our website emphasizes American English and leans towards usage rules in the Chicago Manual of Style.

  29. Wade says:

    Thanks for the article. Now I feel assured that I am using ensure corrrectly.

  30. Antony Le says:

    Super awesome! Thanks

  31. Jared says:

    A more complete definition of insure would be to protect from loss, not only to cover with an insurance policy, while ensure is to make certain. The use by the NRA is correct.

    I can assure you, that I have ensured compliance to D.O.T regulations by insuring my vehicle.

    Rest assured, that insuring our rights will ensure the prosperity of our nation.

    • Pat Simco says:

      “Rest assured, that insuring our rights will ensure the prosperity of our nation.”

      Insuring our rights will ensure accrual of wealth to insurance industry (private and/or public), but people can not really rest assured of their rights. They must constantly organize and act to ensure their rights against greed, corruption, incompetence, apathy, and …

  32. Brandy Smith says:

    I have often been told that the word tips was derived from the words To Insure Prompt Service. Do you have any insight on the background of this word? Also, in this context should the word be ensure?

  33. Lauren says:

    Seems like you “assure” people, “insure” items, and “ensure” thoughts/ideas….

  34. JMCabanis says:

    Here’s a puzzler for you: I am editing a section of a document about quality assurance practices. In it, the writer says that “regular walkthroughs by management assure that the product will function correctly.”
    I think that should be ensure. But it is Quality Assurance. What do you think?

    • You are correct that assure is more about saying than doing and ensure is more about doing what is necessary to achieve that assurance. Since this document deals with quality assurance and the word assurance implies a promise, it is not surprising that the company chose the word assure.

      • Kevin B. says:

        But assurance is about communicating confidence. How can a walk-through communicate? I think Quality Assurance should be Quality Ensurance, but ensurance is an obselete word, as you mention in a later post.
        By the way, Quality Control is something else.

  35. Andrew says:

    Please review the United States Constitution where insure is used frequently. The preamble states, “insure domestic tranquility.” I think the use of the word “insure” was intentional to reflect language consistent with the Constitution.

  36. KP says:

    Could you please comment on this sentence? My eyes want to see “ensure” here.

    “To assure proper credit to your account, please detach and include the bottom portion of your invoice.”

  37. Alicia says:

    Great explanation! It was descriptive and concise. Thanks

  38. Bob says:

    On the topic of ensure vs. assure, is it also correct to say that “one ensures that things will get done” while “one assures people that things will get done”?

  39. Todd says:

    According to this definition, the US Constitution is wrong. The phrase “insure a more perfect union” should be “ensure a more perfect union”

    • Yes, Josh pointed that out in his comment of September 25, 2009.

    • Corey Andreasen says:

      Actually, “insure a more perfect union” is not the phrase. It’s “insure domestic tranquility,” but your point is correct.

      • That’s correct. As Josh’s September 25, 2009, message pointed out, the wording is “We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility …”

  40. Bob says:

    What about the concept of “assuring compliance” in the context of complying with some standard or regulation? That usage is pretty common in business and software environments, with companies even using that construction in their names as well. Are they all using “assure” incorrectly there, or is that an accepted use in that specific context?

  41. Marcos says:

    Thnaks for the information provided! it helped.

  42. Mackenzie says:

    Dunkin donuts does it wrong too.

  43. Nate says:

    I was reading the Code of Federal Regulations, and noticed this phrase, “Written procedures shall be established and followed prescribing a system … to insure that the reprocessed batches will conform …” (21 CFR 211.115). The use of insure seemed odd to me which brought me here. According to Jane’s definition the CFR is wrong, which is more concerning to me than the above examples (i.e. NRA) since we are regulated by the FDA and verbage can be very significant. The federal government’s choice to overlap insure with ensure definitely ought to weigh into this discussion.

    • This is an old-school usage of insure that The New Yorker also employs. In our opinion, it can cause confusion. If you monitor future rulemakings, during the public comment period you might inquire as to what kind of insurance they are offering.

  44. Robert says:

    I believe their intent is to convey that joining the NRA helps provide a level of insurance that your gun rights will be protected. “To have what is necessary for success” makes no sense in this context.

  45. Rob Feight says:

    Thank you for presenting clarification for us information seekers wishing to keep this a literary competent world.

  46. kevin says:

    I came to this site after I questioned how I used assure in a post. I am still confused and my post was; I thought I was being helpful and it would assure the help showed up.

  47. JOE says:

    so assure=assurance and insure=insurance then what does ensure=?

    • The Merriam-Webster Unabridged Dictionary notes that the word ensurance is an obsolete word meaning insurance. We no longer use this word in the English language. Therefore, there is no noun related to ensure.

  48. Charles says:

    Obviously, there is a difference between ensure and assure. However, it seems to me that “guarantee” could be substituted wherever either word is used to convey the same meaning of virtually any sentence.

  49. Van Plaza says:

    I just came across this discussion today. Would it not be simpler to just use “to make sure” something does or does not happen instead of ensure?

    • says:

      Yes, although your verb phrase includes more words, you would be justified in using “to make sure” to ensure clarity (precise pun intended). The article’s primary aim is to help writers further understand the distinctions among the similar verbs when the goal is to use only one word.

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