I'll tell you what vs Mark my words

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

I'll tell you what

InformalTop 3,000 (common)

Mark my words

InformalBeyond 10,000 (less common)
Most common: I'll tell you what
 I'll tell you whatMark my words
Pronunciation🇬🇧 //aɪl tɛl jʊ wɒt//🇺🇸 //aɪl tɛl ju wɑt//🇬🇧 //mɑːk maɪ wɜːdz//🇺🇸 //mɑrk maɪ wɜrdz//
MeaningLet me explain something to you.Remember what I say, it will be important.
ExampleI'll tell you what, this food is amazing!Mark my words, he will regret this decision.
RegisterInformalInformal
How commonTop 3,000 (common)Beyond 10,000 (less common)
CollocationsI'll tell you what happened, I'll tell you what it means, I'll tell you what to domark my words, remember my words, mark these words, mark those words
AntonymsI won't tell you, I'll keep it a secret, I refuse to say-
Common mistakesUsing it in very formal contexts., Confusing it with 'I'll tell you that'., Not recognizing it as a phrase to emphasize a point.Misplaced as a formal statement., Using it without context or meaning., Not using it with a prediction or warning.
Usage notesUsed in conversations to emphasize a point or introduce a strong opinion, often in informal settings. Not suitable for formal discussions.Use when you want to emphasize the seriousness of what you are saying. It's used in spoken language, often with a predictive tone.

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I'll tell you what
Mark my words

Frequently asked questions: I'll tell you what vs Mark my words

What's the difference between I'll tell you what and Mark my words?

I'll tell you what: Let me explain something to you. Mark my words: Remember what I say, it will be important.

Which is more common: I'll tell you what and Mark my words?

I'll tell you what is the most common in everyday English.

Can you show an example of each?

I'll tell you what: I'll tell you what, this food is amazing! Mark my words: Mark my words, he will regret this decision.

Can I use I'll tell you what and Mark my words interchangeably?

Not always. I'll tell you what and Mark my words 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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