If vs Whether

When to use each in English, with meaning, register, and examples.

If

High-frequency chunk A1 conjunction

Whether

Top 1,000 (very common) B1 conjunction

	If	Whether
Pronunciation	🇬🇧 /["/ɪf/"]/ 🇺🇸 /["/ɪf/"]/	🇬🇧 /["/ˈweðə(r)/"]/ 🇺🇸 /["/ˈweðər/"]/
Meaning	used to talk about a situation that may happen.	If something is true or not.
Example	If it rains tomorrow, we will stay inside.	He seemed undecided **whether** to go **or** stay.
Register	Neutral	Neutral
How common	High-frequency chunk	Top 1,000 (very common)
CEFR level	A1	B1
Part of speech	conjunction	conjunction
Collocations	if you want, if necessary, if possible, if I were you, if it rains	whether or not, decide whether, whether to choose
Antonyms	unless	if not, unless
Common mistakes	Using 'if' with incorrect verb tenses (e.g., 'if I will go' instead of 'if I go')., Confusing 'if' with 'whether' in non-conditional contexts., Neglecting to use 'if' when introducing a condition.	Confusing 'whether' with 'if' in certain contexts., Using 'whether' without a second alternative., Omitting 'if' when it should be used instead of 'whether'.
Usage notes	Use 'if' to introduce conditional situations. Suitable for both spoken and written contexts. Avoid in very formal writing where alternatives like 'should' might be preferred.	Use 'whether' to introduce options or alternatives, especially when discussing choices. It's appropriate in both spoken and written English, but can be formal in certain contexts. Avoid using it when only one option exists.

See it in real clips

Sherlock › S1 E1

Just so I know whether I could have beaten you.

the question of whether we're a hung jury or not.

Peaky Blinders › S1 E1

whether or not you're lying.

Sherlock › S1 E1

Just so I know whether I could have beaten you.

the question of whether we're a hung jury or not.

Whether

Frequently asked questions: If vs Whether

What's the difference between If and Whether?

If: used to talk about a situation that may happen. Whether: If something is true or not.

Which is more advanced: If and Whether?

Whether is the highest level, at B1, on the CEFR scale.

Are If and Whether the same CEFR level?

If: A1, Whether: B1 on the CEFR scale.

What part of speech are If and Whether?

If: conjunction, Whether: conjunction.

Can you show an example of each?

If: If it rains tomorrow, we will stay inside. Whether: He seemed undecided **whether** to go **or** stay.

Can I use If and Whether interchangeably?

Not always. If and Whether are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.