'If' Versus 'Whether'

"If" and "whether" are often interchangeable, but sometimes using one or the other will change the meaning of your sentence. Here are some examples and an explanation.

Mignon Fogarty
4-minute read
Episode #831

Today's topic is "whether" — not rain or snow, but whether w-h-e-t-h-e-r, as in whether you like it or not, it's the topic.

First, let's figure out when to use "whether" and when to use "if."

'If' Versus 'Whether'

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Although in informal writing and speech people often use "if" and "whether"  interchangeably, in formal writing, such as in technical writing at work, it's a good idea to make a distinction between them because the meaning can sometimes be different depending on which word you use. The formal rule is to use "if" when you have a conditional sentence and "whether" when you are showing that two alternatives are possible. Some examples will make this more clear.

Here's an example where the two words could be interchangeable:

Squiggly didn't know whether Aardvark would arrive Friday.

Squiggly didn't know if Aardvark would arrive Friday.

In either sentence, the meaning is that Aardvark may or may not arrive Friday.

Now, here are some examples where the words are not interchangeable:

Squiggly didn't know whether Aardvark would arrive Friday or Saturday.

Because I used "whether," you know that there are two possibilities: Aardvark will arrive Friday, or Aardvark will arrive Saturday.

Now see how the sentence has a different meaning when I use "if" instead of "whether":

Squiggly didn't know if Aardvark would arrive Friday or Saturday. 

Now in addition to arriving on Friday or Saturday, it's possible that Aardvark may not arrive at all. 

These last two sentences show why it is better to use "whether" when you have two possibilities, and that is why I recommend using "whether" instead of "if" when you have two possibilities, even when the meaning wouldn't change if you use "if." It's safer and more consistent.

Here's a final pair of examples:

Call Squiggly if you are going to arrive Friday. 

Call Squiggly whether or not you are going to arrive Friday. 

The first sentence is conditional. "Call Squiggly if you are going to arrive Friday," means Aardvark only needs to call if he is coming.

The second sentence is not conditional. "Call Squiggly whether or not you are going to arrive Friday," means Aardvark needs to call either way.

To sum up, use "whether" when you have two discrete choices or mean "regardless of whether," and use "if" for conditional sentences.


'Whether' Versus 'Whether or Not'

That last example is also a good lead in to a second topic: When do you need an "or not" after "whether"? Why did I say, "Call Squiggly whether or not you are going to arrive Friday?"

Often, the "or not" is just extra fluff and should be left off. In my first example, where I said, "Squiggly didn't know whether Aardvark would arrive Friday," adding "or not" wouldn't change the meaning or emphasis. "Squiggly didn't know whether or not Aardvark would arrive Friday," means the same thing as "Squiggly didn't know whether Aardvark would arrive Friday." "Or not" doesn't add anything, so leave it out.

On the other hand, you need the full phrase "whether or not" when you mean "regardless of whether." It shows that there is equal emphasis on both options.

Call Squiggly regardless of whether you are going to arrive Friday.

Call Squiggly whether or not you are going to arrive Friday.

Finally, a listener wrote to say that her boss was driving her up the wall by saying "rather or not" instead of "whether or not." So I'll add that "rather or not" is incorrect; "whether" is a conjunction and "rather" is an adverb, and they are not interchangeable. "Whether or not" is the correct way to show that there are two possibilities or that you mean "regardless of whether."

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Using the wrong word can change the meaning of your sentence! Use "if" in conditional sentences and "whether" when writing about two alternatives.


Bernstein, T.M. Do's Don'ts and Maybes of English Usage, Times Books: New York. 1977, p.237.

Garner, B. "Whether." Garner's Modern English Usage, fourth edition. Oxford University Press. 2016, p. 960.

if. American Heritage College Dictionary, fourth edition. Houghton Mifflin Company:Boston. 2007, p. 689.

rather. Dictionary.comhttp://dictionary.reference.com/browse/rather (accessed July 6, 2021).

Kilian, C. "Rather? Whether?" Ask the English Teacher. May 26, 2006. http://crofsblogs.typepad.com/english/2006/05/rather_whether.html (accessed July 6, 2021).

whether. Dictionary.comhttp://dictionary.reference.com/browse/whether (accessed July 6, 2021).

About the Author

Mignon Fogarty

Mignon Fogarty is the founder of Quick and Dirty Tips and the author of seven books on language, including the New York Times bestseller "Grammar Girl's Quick and Dirty Tips for Better Writing." She is an inductee in the Podcasting Hall of Fame, and the show is a five-time winner of Best Education Podcast in the Podcast Awards. She has appeared as a guest expert on the Oprah Winfrey Show and the Today Show. Her popular LinkedIn Learning courses help people write better to communicate better.