The question of when to use if vs whether in English can be quite confusing. These two words have a similar meaning and can sometimes be used interchangeably – but sometimes they can’t!
So, if you have been wondering about the difference between if and whether, the answer is about to become clearer.
We’ll explain in which situations it’s fine to use whether or if, and in which situations only one of them is correct grammatically.
If vs whether: the short answer
Let’s begin with the short version of the answer to the question: When should you use if and whether?
Simply put, if states a condition and whether indicates a choice between options. For example:
- I don’t know whether it will rain this afternoon.
- She’s been thinking about whether to learn the violin.
- I won’t go out if it rains.
- If she learns the violin, she will be able to play beautiful music.
However, you may sometimes hear whether and if used interchangeably.
For example, the first sentence above could be said as ‘I don’t know if it will rain this afternoon’. So, let’s look at the rules in more detail.
Using if and whether interchangeably
The following three situations are all examples of sentences when either if or whether may be used.
1. To answer a yes/no question indirectly
If someone asks a question that could be answered with ‘yes’ or ‘no’, but you want to give a more complex answer of uncertainty, you may use if or whether. Both are correct. For example:
Q: Are you coming to my party on Saturday?
A: I don’t know whether I will have time.
A: I don’t know if I will have time.
Q: Has he eaten dinner yet?
A: I’m not sure whether he’s eaten yet.
A: I’m not sure if he’s eaten yet.
2. To form an indirect yes/no question
Sometimes we ask a question without phrasing it as a direct question. This is known as an indirect or embedded question. In this case, both if and whether are ok to use.
For example, instead of saying ‘Is the light on?’ you could say:
- Could you tell me whether the light is on?
- Could you tell me if the light is on?
We can also use this sentence structure to think out loud:
- I wonder whether they had a good time.
- I wonder if they had a good time.
3. In a whether/if … or … construction
When discussing two possible options, both whether and if may be used:
- I wonder whether it will be sunny or cloudy tomorrow.
- I wonder if it will be sunny or cloudy tomorrow.
- I don’t know whether she’s in a good mood or a bad mood.
- I don’t know if she’s in a good mood or a bad mood.
- He doesn’t care whether the room is painted blue, yellow or green.
- He doesn’t care if the room is painted blue, yellow or green.
However, if there are other unmentioned options then it is better to use ‘if’ instead of ‘whether’.
E.g. ‘I wonder if we will have pizza or burgers for dinner tonight’ doesn’t necessarily mean these are the only two possibilities; just that you are thinking about these two specifically.
Situations that require whether
In the following examples you must use ‘whether’ to form the sentence correctly.
1. After prepositions:
- I want to ask you about whether we should cut our advertising budget.
- They had a heated discussion over whether they should buy a new car.
- Our client would like to arrange a meeting regarding whether we have met our targets this month.
2. Before infinitives:
- I’m not sure whether to go shopping or do the ironing.
- She needs to decide whether to learn to play the guitar.
- I don’t know whether to tell them the bad news.
Situations that require if
Finally, here is one sentence structure which requires you to use if, not whether:
1. To state a condition:
- I will come to your party if I have time.
- You will be allowed to watch TV tonight if you finish your homework first.
- If he passes his test, we will eat out to celebrate.
You can vary your vocabulary by using some transition words for conditional results.
Using whether or not
In many of the examples above, the meaning whether or not is implied because we have situations with only two possible outcomes.
For example, ‘I wonder whether they had a good time’ is the same as saying ‘I wonder whether or not they had a good time’. The or not is not required.
Similarly, ‘I don’t know whether I will have time’ conveys the same meaning as ‘I don’t know whether I will have time or not’.
In other situations, we use whether or not to mean regardless of whether and in these situations it is necessary to include or not, for example:
- We’ll go to the zoo whether or not it rains.
- They’ll have a good time whether I’m there or not.
- You should service your car regularly whether or not you use it.
Note that or not doesn’t have to immediately follow whether, as in the second sentence.
And that’s really all you need to know about how to use if vs whether. If you have a sentence you’re unsure about, you can leave a comment below.
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