Of course vs Surely

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

Of course

Top 1,000 (very common)

Surely

Top 2,000 (common) B1 adverb

Most common: Of course

	Of course	Surely
Pronunciation	🇬🇧 //əv kɔːs// 🇺🇸 //əv kɔrs//	🇬🇧 /["/ˈʃʊəli//ˈʃɔːli/"]/ 🇺🇸 /["/ˈʃʊrli/"]/
Meaning	Definitely, it's obvious.	certainly; without a doubt
Example	Are you joining us for dinner tonight? Of course!	Surely we should do something about it?
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 2,000 (common)
CEFR level	-	B1
Part of speech		adverb
Collocations	of course not, of course yes, of course you can, of course it is	surely believe, surely know, surely must
Antonyms	-	doubtfully, unsure
Common mistakes	Using it in formal writing where a different expression is needed., Confusing it with other affirmations like 'certainly' or 'definitely'.	Confusing 'surely' with 'sure' — 'sure' can be an adjective., Using 'surely' as a response when a simple 'yes' would suffice., Omitting 'surely' in a sentence where it clarifies certainty.
Usage notes	Used in informal and formal situations to affirm something obvious. Avoid in highly formal writing.	Use 'surely' to express certainty. It’s appropriate in both spoken and written contexts but is more common in formal discussions. Avoid using it in very casual conversations where simpler words like 'definitely' might fit better.

See it in real clips

Of course.

Agatha Christies Poirot › S1 E1

You know her, of course.

And, of course, I paid my respect to Bubba himself.

Of course.

Agatha Christies Poirot › S1 E1

You know her, of course.

Of course

Yes, sir, they surely did.

Surely

Frequently asked questions: Of course vs Surely

What's the difference between Of course and Surely?

Of course: Definitely, it's obvious. Surely: certainly; without a doubt

Which is more common: Of course and Surely?

Of course is the most common in everyday English.

Can you show an example of each?

Of course: Are you joining us for dinner tonight? Of course! Surely: Surely we should do something about it?

Can I use Of course and Surely interchangeably?

Not always. Of course and Surely 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.