Whether vs If

B1 Intermediate

Whether and if are used to introduce indirect questions or choices between two possibilities. While often interchangeable, whether is preferred in formal contexts and specific grammatical structures.

Overview

Both whether and if are used to report a 'yes/no' question or to talk about uncertainty. They connect a main clause to a dependent clause when there are two possible options (usually 'yes' or 'no').

Form

subject + verb (e.g., wonder/ask) + whether/if + subject + verb

In most indirect questions, both words follow a verb of asking or thinking. Note that the word order in the dependent clause is the same as a statement (subject + verb), not a question.

Key Differences

Use whether when you want to sound more professional or when the clause follows a preposition.

Feature	Whether	If
Formality	More formal and academic.	More common in daily speech.
After Prepositions	Required (e.g., 'depends on whether').	Incorrect.
Before 'to-infinitive'	Required (e.g., 'whether to go').	Incorrect.
With 'or not'	Can be followed immediately by 'or not'.	'Or not' must come at the end of the clause.

Examples

Common mistakes

I am thinking about if I should quit.
I am thinking about whether I should quit.
Use whether after a preposition like 'about'.
I don't know if or not he is coming.
I don't know whether or not he is coming.
Only whether can be followed immediately by 'or not'.

Practice

We need to decide ______ we should hire a new manager. (Both are possible, but choose the more formal one)
Show answer
whether
Answer:whether
Why:While 'if' is grammatically possible here, 'whether' is the standard choice for formal decisions and professional writing.
I'm not sure ______ to call him now or wait until tomorrow.
Show answer
whether
Answer:whether
Why:Only 'whether' can be followed directly by a 'to-infinitive' (to call).
Everything depends on ______ the flight arrives on time.
Show answer
whether
Answer:whether
Why:'Whether' must be used after a preposition (on).