Of course vs Yes sir I do

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

Of course

Top 1,000 (very common)

Yes sir I do

Beyond 10,000 (less common)

Most common: Of course

	Of course	Yes sir I do
Pronunciation	🇬🇧 //əv kɔːs// 🇺🇸 //əv kɔrs//	🇬🇧 //jɛs sɜːr aɪ duː// 🇺🇸 //jɛs sɜr aɪ du//
Meaning	Definitely, it's obvious.	An affirmative response indicating agreement or willingness.
Example	Are you joining us for dinner tonight? Of course!	When asked if he would follow orders, he replied, 'Yes sir, I do'
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Beyond 10,000 (less common)
Collocations	of course not, of course yes, of course you can, of course it is	respond with 'Yes sir', say 'Yes sir' to commands, use 'Yes sir' in formal settings
Common mistakes	Using it in formal writing where a different expression is needed., Confusing it with other affirmations like 'certainly' or 'definitely'.	Using in informal situations., Confusing with 'Yes, I do' which lacks the respectful tone., Not following with additional context or information.
Usage notes	Used in informal and formal situations to affirm something obvious. Avoid in highly formal writing.	Typically used in formal or respectful contexts, often in military or service settings. May be seen as overly formal in casual conversations.

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, I do.

Yes sir I do

Frequently asked questions: Of course vs Yes sir I do

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

Of course: Definitely, it's obvious. Yes sir I do: An affirmative response indicating agreement or willingness.

Which is more common: Of course and Yes sir I do?

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 I do: When asked if he would follow orders, he replied, 'Yes sir, I do'

Can I use Of course and Yes sir I do interchangeably?

Not always. Of course and Yes sir I do 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.