Hey vs Oh

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

Hey

Informal Top 1,000 (very common) A1 exclamation

Oh

Informal High-frequency chunk A1 exclamation

	Hey	Oh
Pronunciation	🇬🇧 /["/heɪ/"]/ 🇺🇸 /["/heɪ/"]/ Hear Hey	🇬🇧 /["/əʊ/"]/ 🇺🇸 /["/əʊ/"]/ Hear Oh
Meaning	A casual greeting used to say hello.	A sound made when surprised or when realizing something.
Example	Hey, can I just ask you something?	‘I saw Ben yesterday.’ ‘Oh yes, how is he?’
Register	Informal	Informal
How common	Top 1,000 (very common)	High-frequency chunk
CEFR level	A1	A1
Part of speech	exclamation	exclamation
Collocations	say hey, hey there, hey buddy, hey dude	oh my, oh no, oh really
Antonyms	goodbye, farewell, bye	No, Nah
Common mistakes	Using 'hey' in formal emails or letters., Spelling it as 'hay' when greeting someone.	Overusing it in formal contexts., Confusing it with 'ohh' which indicates a longer realization., Not using appropriate punctuation in writing.
Usage notes	Primarily used in informal situations among friends or acquaintances. It's less appropriate in formal contexts or professional settings. Avoid using it with people you don't know well.	Commonly used in casual conversation or texts when expressing surprise, understanding, or mild disappointment. Not suitable for formal writing or speech.

Frequently asked questions: Hey vs Oh

What's the difference between Hey and Oh?

Hey: A casual greeting used to say hello. Oh: A sound made when surprised or when realizing something.

Are Hey and Oh the same CEFR level?

Hey: A1, Oh: A1 on the CEFR scale.

Can I use Hey and Oh interchangeably?

Not always. Hey and Oh 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.