Certainly vs Of course I read it

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

Certainly

Top 1,000 (very common)A2adverb

Of course I read it

Top 5,000 (fairly common)
Most common: Certainly
 CertainlyOf course I read it
Pronunciation🇬🇧 /["/ˈsɜːtnli/"]/🇺🇸 /["/ˈsɜːrtnli/"]/🇬🇧 //əv kɔːs aɪ rɛd ɪt//🇺🇸 //əv kɔrs aɪ rɛd ɪt//
MeaningDefinitely; for sure.It's natural for me to have read it.
ExampleWithout treatment, she will **almost certainly** die.Of course I read it; it was really interesting!
RegisterNeutralNeutral
How commonTop 1,000 (very common)Top 5,000 (fairly common)
CEFR levelA2-
Part of speechadverb
Collocationscertainly agree, certainly possible, certainly not, certainly true, certainly yesOf course I agree, Of course I know, Of course you can
Antonymsuncertainly, doubtfully-
Common mistakes'Certainly' is often incorrectly used in place of 'certain' in adjectives., Learners might confuse 'certainly' with 'definitely' without noticing the subtle nuance., Some learners use 'certainly' in inappropriate contexts, such as casual greetings.Using 'of course' in contexts where it's not obvious, making it sound condescending., Misplacing the phrase in sentences, losing its intended emphasis., Translating directly from another language, which may sound awkward.
Usage notesUse 'certainly' when you want to emphasize affirmation or agreement. It is more formal than 'sure' and works well in professional settings, but might feel too strong in casual conversations.Use this phrase to express a natural understanding or expectation. It's typically informal but can be slightly formal in certain contexts.

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Certainly
Of course I read it

Frequently asked questions: Certainly vs Of course I read it

What's the difference between Certainly and Of course I read it?

Certainly: Definitely; for sure. Of course I read it: It's natural for me to have read it.

Which is more common: Certainly and Of course I read it?

Certainly is the most common in everyday English.

Can you show an example of each?

Certainly: Without treatment, she will **almost certainly** die. Of course I read it: Of course I read it; it was really interesting!

Can I use Certainly and Of course I read it interchangeably?

Not always. Certainly and Of course I read it 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.

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