I'll have you know vs Just so you know

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

I'll have you know

Beyond 10,000 (less common)

Just so you know

InformalTop 2,000 (common)
Most formal: I'll have you knowMost common: Just so you know
 I'll have you knowJust so you know
Pronunciation🇬🇧 //aɪl hæv jʊ noʊ//🇺🇸 //aɪl hæv jʊ noʊ//🇬🇧 //dʒʌst səʊ jʊ nəʊ//🇺🇸 //dʒʌst soʊ jʊ noʊ//
MeaningI want you to know something important.A way to tell someone information casually.
ExampleI'll have you know I graduated at the top of my class.Just so you know, the meeting has been moved to 3 PM.
RegisterNeutralInformal
How commonBeyond 10,000 (less common)Top 2,000 (common)
CollocationsI'll have you know I'm an expert, I'll have you know it's true, I'll have you know I was here firstjust so you know, I wanted to tell you, just so you know, the time has changed, just so you know, it's not confirmed yet
Common mistakesUsed in overly formal situations when it sounds out of place., Misinterpreted as a threat instead of a statement of fact., Confused with 'I want you to know' which can be softer.Used in formal emails where a direct statement is needed., Confused with phrases like 'for your information' for more formal contexts.
Usage notesUse this phrase to emphasize a point or express pride. It's often used in disputes or to assert oneself. Avoid in very formal contexts.Use this phrase when you want to inform someone without being too formal. It works well in conversations among friends.

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I'll have you know
Just so you know

Frequently asked questions: I'll have you know vs Just so you know

What's the difference between I'll have you know and Just so you know?

I'll have you know: I want you to know something important. Just so you know: A way to tell someone information casually.

Which is more formal: I'll have you know and Just so you know?

I'll have you know is the most formal of these.

Which is more common: I'll have you know and Just so you know?

Just so you know is the most common in everyday English.

Can you show an example of each?

I'll have you know: I'll have you know I graduated at the top of my class. Just so you know: Just so you know, the meeting has been moved to 3 PM.

Can I use I'll have you know and Just so you know interchangeably?

Not always. I'll have you know and Just so you know 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.