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What’s the difference between If and Whether?

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Have you ever found yourself unsure whether to use If and Whether in a sentence? While these two words are often used interchangeably, they differ slightly in structure, formality, and usage. In this article, we’ll break down the key differences between If and Whether, show you when to use each, and provide examples to help you master them with confidence.

What are If and Whether? English knowledge about the If and Whether structures

I. What does If mean?
II. What does Whether mean?
III. When to use If and Whether
1. 1. In reported (indirect) questions
2. 2. With “or not”
IV. Difference between If and Whether
VI. Common mistakes to avoid when using If and Whether
VII. If and Whether exercises with answers
1. 1. Exercises
2. 2. Answer keys

I. What does If mean?

If (pronounced /ɪf/) functions primarily as a conjunction, though it can also be used as a noun in certain contexts.

As a conjunction, it introduces a condition, possibility, or contrast. For example:
- I'll pay you double if you get the work finished by Friday.
- They're great kids, even if they can be demanding.
As a noun, If refers to something uncertain or undecided. For example: There's a big if hanging over the project.

Common idioms with If:

Common idioms with If	Meaning	Example
If and when	Used to emphasize uncertainty about a future event, indicating that it may or may not happen	If and when you decide to come visit, let me know so I can prepare a room for you.
If anything	Used to suggest that the opposite of what has been previously stated may be true or more relevant	He's not lazy; if anything, he works too hard.
If I were you	Used to give advice or suggestions, indicating what the speaker would do in the listener's situation	If I were you, I would start studying for the exam now instead of waiting until the last minute.
If need be	Used to imply that something will be done if necessary	We can postpone the meeting if need be, but I would prefer to keep it as scheduled.
If you will	Used to indicate that the speaker is giving permission or acknowledging someone else's wish or preference	He’s the Mozart of our generation, if you will.
If all else fails	Used to express that a specific action will be taken only when other options have been exhausted	If all else fails, we can always move to another city and start over.
If only	Used to express a wish that a situation were different or to express regret about something that cannot be changed	If only I had known about the traffic, I would have left earlier.
If the worst comes to the worst	Used to indicate what someone will do if the most unfavorable situation occurs	If the worst comes to the worst, we can always sell the house and move into a smaller apartment.

II. What does Whether mean?

Whether (pronounced /ˈwɛð.ər/) is also a conjunction, often used to indicate choices or uncertainty between two alternatives.

She asked me whether I was interested in working for her.
Whether or not Daisy resigned from her job is none of my business.

III. When to use If and Whether

While both words can be used in indirect (reported) questions, there are certain contexts where only one is appropriate.

1. In reported (indirect) questions

Use either “if” or “whether” when turning yes/no questions into indirect speech.

S + V + whether/if + S + V

For example:

John asked if his mother could pick him up after school.
Jenny and I wanted to know whether our class were going to eat out.

2. With “or not”

When indicating both possibilities, “whether” is typically preferred, especially in more formal or complete constructions.

S + V + whether/if + S + V + or not

S + V + whether or not + S + V

For example:

I called Harry to ask whether he got married or not.
Our team has to process the meeting whether or not the boss is here.

Note: Clarifying “Whether or” vs. “Whether or not”

"Whether or" introduces a clear choice. For example: I don’t know whether Harry is laughing or crying.
"Whether or not" emphasizes both possible outcomes, including negation. For example: Whether or not Peter likes it, he will have to learn this subject.

IV. Difference between If and Whether

Although both words can introduce indirect yes/no questions, their usage differs in some contexts:

Difference between Whether and If

Similarities

Both If and Whether are used to introduce Yes/No questions in indirect speech. For example:

John asked Anna whether she felt well.
Jenny is not sure if they have decided.

If and Whether differences

After the verb "discuss", "Whether" is preferred over "If."
- We discussed whether he should be hired.
- They discussed whether to invest in the new idea.
After prepositions, only "Whether" can be used.
- Daisy talked about whether she should go or not.
- I looked into whether he should stay.
With the infinitive form of verbs, only "Whether" is used.
- Kathy can’t decided whether to buy the house or wait.
- Peter considered whether to give up the position or quit next month.
"Whether" is often used in more formal or diplomatic contexts, while "If" is typically used in casual and informal situations.
- Let me know whether Anna will be able to attend the meeting.
- Kathy asked if Sara had seen that film.

VI. Common mistakes to avoid when using If and Whether

Many English learners misuse If and Whether in writing and speech. Here are a few typical errors and how to fix them:

Mistakes when using If vs Whether	Example
Using “if” before an infinitive	Sara is not sure if to get a new telephone. ➡ ❌ Sara is not sure whether to get a new telephone. ➡ ✅
In indirect questions, use Either:	Daisy can’t say either using Facebook is harmful or beneficial. ➡ ❌ Daisy can’t say whether using facebook is harmful or beneficial. ➡ ✅
Omitting “if” or “whether” in reported speech	Peter wants to find out the rooms have a phone and television or not. ➡ ❌ Peter wants to find out whether/if the rooms have a phone and television or not. ➡ ✅
Using “if or not”	Can you tell me if or not you are interested in studying abroad? ➡ ❌ Can you tell me whether or not you’re interested in studying abroad? ➡ ✅

VII. If and Whether exercises with answers

Now that you’ve learned the rules and differences, try applying them in context with some practice questions. This is the best way to reinforce your understanding and avoid common pitfalls.

1. Exercises

Exercise 1: Fill in the blanks with the appropriate If or Whether.

I don’t know ___Jenny is coming or not, she doesn’t mention the party.
Kathy considered___ to continue studying her major or take up a Marketing course.
Tell me___ John can come to the party or not.
Anna’s mother is still wondering ___she will choose the red car or the blue car.
Kathy called John to ask ____ he finished the report or not.

Exercise 2: Rewrite the sentences using Whether versus If.

“Do you want to eat this candy?”

➡ Sara asked John _______________________________________.

“Have you visited Korea?”

➡ Anna asked Peter _______________________________________.

“Does Jenny like coffee?”

➡ Harry wanted to know _______________________________________.

“Is Peter playing football?”

➡ Kathy wondered _______________________________________.

“Are you learning Japanese?”

➡ Daisy asked me _______________________________________.

2. Answer keys

Exercise 1	Exercise 2
If Whether If If Whether	Sara asked John if/whether he wanted to eat that candy. Anna asked Peter if/whether he had visited London. Harry wanted to know if/whether Jenny liked coffee. Kathy wondered if/whether Peter was playing football. Daisy asked me if/whether I was learning Japanese.

Understanding how to use If and Whether correctly is crucial for expressing conditions, making decisions, and forming indirect questions. While they may seem interchangeable at first glance, their usage can vary depending on formality, structure, and specific grammar rules. Practice regularly, pay attention to the context, and soon their usage will come naturally. For more helpful tips on English grammar and usage, be sure to follow PREP’s language learning updates!

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Hien Hoang

Product Content Admin

Hi I'm Hien, and I am currently serving as an Product Content Administrator at Prep Education. With over five years of experience in independent online IELTS study and exam preparation, I am confident in my ability to support learners in achieving their highest possible scores.