If Vs Whether: What’s the Difference?

If vs whether can be confusing because sometimes these words are interchangeable, while other times they have very different meanings.

When words in the English language have similar meanings, they are often considered interchangeable. However, people who want to write without grammatical errors must learn how to use these words correctly. The prepositions if vs whether can be one commonly misunderstood pair in English writing.

Though both if and whether show a situation that is not quite certain, they are not the same. Differentiating between them starts with understanding their meanings. Here is a closer look at what these prepositions mean and when to use them.

If Vs Whether – Making The Preposition Fit The Sentence

Even though if and whether have very similar meanings, they are not the same. There are specific rules in American English that dictate when to use them. Here are some of those rules.

1. Use If for a Conditional Sentence

If you are using a preposition in a sentence that states a condition, then you will use if. Here are some examples:

• If the weather is good, we will go to the park instead of the bowling alley.
• Please reach out if you have any further questions.

Both of these are conditional statements, so if is the correct word to use.

2. Use Whether for Two Options or Alternatives

If the sentence states two specific choices, then the preposition to use is whether. Here is an example sentence:

• Please let us know whether you are going to stay home or come with us.

In this example, the alternatives are to go or stay home, so whether is correct. 

Sometimes the sentence’s meaning dictates which one to use. For instance, both of these are correct:

• Please let us know whether you will arrive Friday or Saturday.
• Please let us know if you will arrive Friday or Saturday.

In the first sentence, the choice is between Saturday and Friday for arrival because the writer used whether. In the second sentence, the choices are Friday, Saturday, or no arrival during that time frame because the writer used if.

3. Use Whether Before an Infinitive

If you are introducing an infinitive verb, you need to use whether. Here is an example:

• He didn’t know whether to laugh or to cry.

This makes sense according to English grammar rules. However, the following sentence does not:

• He didn’t know if to laugh or to cry.

4. Use Whether for “Whether or not”

In a sentence where you could substitute the preposition with the phrase “whether or not,” then you need to use whether. Often, the “or not” is not necessary and is considered fluff, so it is left off, but if the sentence would make sense with it in there, you need to use whether. Here is an example:

• The teacher didn’t know whether the students were paying attention.

This sentence would also make sense if you wrote:

• The teacher didn’t know whether or not the students were paying attention.

Since the phrase “or not” makes sense, the correct preposition is whether.

5. Use Whether to Introduce Clauses Used as a Subject

When you have a noun clause that serves as the subject of the sentence, use whether to introduce it. Here is an example:

• Whether we leave early or late, we will get to our destination at some point.

This makes sense because you could interchange “whether or not” with whether. 

6. Whether and If Can Be Interchangeable

There are instances where whether and if can be used interchangeably in English grammar. Though in some instances they have different meanings, in other English usage they mean the same thing.

Specifically, if you are asking a question with a yes or no answer, you can use whether or if. Even if you are asking an indirect question, you can use either. For more formal questions, use whether, and for less formal, use if.

A Final Word on If vs Whether

So the answer to when to use whether and when to use if boils down to the way you are using it. For a conditional statement, use the preposition if, but for a decision between two choices, use whether. If you are asking a yes/no question, then use either one.

Some other conditions to use whether include before an infinitive or at the beginning of a subjective clause. It is also the choice to use when “whether or not” is the correct statement.

Keep in mind that it is considered the better choice for informal writing, while whether is a better choice for formal writing. When the rules allow you to use either, choose the right one for your writing type.

FAQs on If vs Whether