CS Sealey

Sydney-based sub-editor, writer and author

The difference between if and whether

TLDR: It’s a bit tricky. Best to read it all.

While some may assume that whether is merely the more formal word to use when if is acceptable, there are instances where the two words are not interchangeable.

if (conjunction)—used to introduce a conditional sentence or clause; ‘despite the possibility that’

‘If it snows tonight, I will make a snowman after breakfast tomorrow morning!’

‘I’m going to that party, even if I have to walk there in the rain!’

He wondered if his little accident had gone unnoticed.

‘Oh, if I must…’

whether (conjunction)—used to express uncertainty with a choice; to express a question; also to indicate one of a number of alternatives expressed must be the case

‘I don’t know whether I should play today, due to my injury.’

‘Could you let me know whether I need to prepare dinner tonight for Tom?’

I decided that I was going to stay home, whether my parents approved or not!

Now, some of these sentences would allow if to replace whether and vice versa. For example:

‘I don’t know if I should play today, due to my injury.’

In this case, the use of whether is merely a more formal choice of wording. However, sometimes, when if replaces whether, the meaning of the sentence changes slightly. For instance:

‘Could you let me know if I need to prepare dinner tonight for Tom?’

This sentence is grammatically correct, however the sentence is now worded to mean that the only answer the asker needs to know is if she DOES need to prepare dinner for Tom. So in this instance, whether is the better word to use, since the asker wants to hear one of two possible answers.

Quite often, whether will be accompanied by or not, though in many instances, the or not is obsolete. For example:

‘I don’t know whether I should play today (or not), due to my injury.’

‘Could you let me know whether (or not) I need to prepare dinner tonight for Tom?’

Note also that the correct position of the or not is not strict. As long as it is grammatically correct, it can follow whether or end your sentence or clause.

But when is the or not compulsory in a sentence? Well, in the instances where whether can be replaced with regardless of whether, then the or not is necessary in the sentence. For example:

I decided that I was going to stay home, whether my parents approved or not!

I decided that I was going to stay home, regardless of whether my parents approved!

It is a bit tricky, I know, but nothing a good bit of practising can’t fix! Good luck.

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