Of course vs You most certainly may

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

Of course

Top 1,000 (very common)

You most certainly may

Formal Beyond 10,000 (less common)

Most formal: You most certainly may Most common: Of course

	Of course	You most certainly may
Pronunciation	🇬🇧 //əv kɔːs// 🇺🇸 //əv kɔrs//	🇬🇧 //juː məʊst ˈsɜːtənli meɪ// 🇺🇸 //ju moʊst ˈsɜrtənli meɪ//
Meaning	Definitely, it's obvious.	You can definitely do this.
Example	Are you joining us for dinner tonight? Of course!	You most certainly may take the day off for your birthday.
Register	Neutral	Formal
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	You may, Best wishes, Without hesitation, It is my pleasure, At your convenience
Common mistakes	Using it in formal writing where a different expression is needed., Confusing it with other affirmations like 'certainly' or 'definitely'.	Using in casual conversations where simpler language would be better., Misplacing the phrase in a sentence; it should stand alone., Confusing with other phrases like 'You can surely do it' which may sound less formal.
Usage notes	Used in informal and formal situations to affirm something obvious. Avoid in highly formal writing.	Used to give permission in a strong, polite way. More suitable in formal contexts; can be overly formal for casual situations.

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

House Of Cards › S1 E1

You most certainly may.

You most certainly may

Frequently asked questions: Of course vs You most certainly may

What's the difference between Of course and You most certainly may?

Of course: Definitely, it's obvious. You most certainly may: You can definitely do this.

Which is more formal: Of course and You most certainly may?

You most certainly may is the most formal of these.

Which is more common: Of course and You most certainly may?

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! You most certainly may: You most certainly may take the day off for your birthday.

Can I use Of course and You most certainly may interchangeably?

Not always. Of course and You most certainly may 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.