Cause vs Why

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

Cause

Top 1,000 (very common) A2 noun

Why

High-frequency chunk A1 adverb

	Cause	Why
Pronunciation	🇬🇧 /["/kɔːz/"]/ 🇺🇸 /["/kɔːz/"]/	🇬🇧 /["/waɪ/"]/ 🇺🇸 /["/waɪ/"]/
Meaning	The reason something happens.	A word used to ask for a reason or explanation.
Example	The cause of the accident was a flat tire.	I asked her why she was late.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	High-frequency chunk
CEFR level	A2	A1
Part of speech	noun	adverb
Collocations	real, root, true, determine, discover, find, be, lie in something, remain, cause of, cause and effect, the cause of death, due to natural causes, good, great, real, have, find, give (somebody), cause for, cause for concern, with good cause, without good cause, deserving, good, just, advance, champion, embrace, for the cause of, in the cause of, in a/​the cause, (all) for a good cause, (all) in a good cause	ask why, wonder why, no reason why
Antonyms	effect, result	because, therefore, so
Common mistakes	Confusing 'cause' with 'because' in sentences., Using 'caused' incorrectly when the present form 'cause' is needed., Incorrectly using 'cause' as a noun instead of a verb.	Omitting 'why' in a question that needs it., Using 'why' in a statement instead of a question., Confusing it with 'when' or 'how'.
Usage notes	Use 'cause' in standard writing and conversation. In formal contexts, you might use 'cause' less frequently, opting for 'cause' instead. Avoid using it in very casual or children's language.	Used to inquire about reasons. Generally suitable for most contexts, but avoid in very formal writing. Often starts a question.

See it in real clips

The Pitt › S1 E1

It can cause heart problems.

Band Of Brothers › S1 E1

For whose cause?

Succession › S1 E1

"Cause it was raining and I didn't want to, um...

The Pitt › S1 E1

It can cause heart problems.

Band Of Brothers › S1 E1

For whose cause?

Cause

Frequently asked questions: Cause vs Why

What's the difference between Cause and Why?

Cause: The reason something happens. Why: A word used to ask for a reason or explanation.

Which is more advanced: Cause and Why?

Cause is the highest level, at A2, on the CEFR scale.

Are Cause and Why the same CEFR level?

Cause: A2, Why: A1 on the CEFR scale.

What part of speech are Cause and Why?

Cause: noun, Why: adverb.

Can you show an example of each?

Cause: The cause of the accident was a flat tire. Why: I asked her why she was late.

Can I use Cause and Why interchangeably?

Not always. Cause and Why 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.