Of course vs Yes sir

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

Of course

Top 1,000 (very common)

Yes sir

Formal Top 2,000 (common)

Most formal: Yes sir Most common: Of course

	Of course	Yes sir
Pronunciation	🇬🇧 //əv kɔːs// 🇺🇸 //əv kɔrs//	🇬🇧 //jɛs sɜː// 🇺🇸 //jɛs sɜr//
Meaning	Definitely, it's obvious.	A respectful way to agree or respond positively.
Example	Are you joining us for dinner tonight? Of course!	When the commander asked if we were ready, I replied, 'Yes sir.'
Register	Neutral	Formal
How common	Top 1,000 (very common)	Top 2,000 (common)
Collocations	of course not, of course yes, of course you can, of course it is	answer yes sir, respond yes sir, say yes sir
Common mistakes	Using it in formal writing where a different expression is needed., Confusing it with other affirmations like 'certainly' or 'definitely'.	Used in informal situations like chatting with friends., Mispronouncing it, making it sound less respectful., Confusing it with 'Yeah' which is too informal.
Usage notes	Used in informal and formal situations to affirm something obvious. Avoid in highly formal writing.	Used in formal or military contexts. Not suitable in casual conversations. Emphasizes respect.

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

- Mellish. - Yes, sir.

Band Of Brothers › S1 E1

Yes, sir.

Oh, yes, sir.

- Mellish. - Yes, sir.

Band Of Brothers › S1 E1

Yes, sir.

Yes sir

Frequently asked questions: Of course vs Yes sir

What's the difference between Of course and Yes sir?

Of course: Definitely, it's obvious. Yes sir: A respectful way to agree or respond positively.

Which is more formal: Of course and Yes sir?

Yes sir is the most formal of these.

Which is more common: Of course and Yes sir?

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! Yes sir: When the commander asked if we were ready, I replied, 'Yes sir.'

Can I use Of course and Yes sir interchangeably?

Not always. Of course and Yes sir 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.