When to use "whether" and when to use "if"
- After prepositions, use only "whether."
I haven't settled the question of whether I'll go back home.
There was a big argument about whether we should move to a new house.
- Use "whether," not "if," before infinitives.
They can't decide whether to get married now or wait.
- Use "whether" when a question-word clause is a subject or complement.
Whether we can stay with my mother is another matter. - (Subject)
The question is whether the man can be trusted. - (Complement)
- Use "whether" if an indirect question is fronted.
Whether I'll have time I'm not sure at the moment.
- Use "whether" in a two-part question with or.
The Directors have not decided whether they will recommend a dividend or reinvest the profits.
Use "whether" after verbs that are more common in a formal style. We discussed whether we should close the shop.
- You may use either "whether" or "if" to introduce indirect questions.
I'm not sure whether [if] I'll have time.