I could kill you for that vs That was a mistake

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

I could kill you for that

InformalBeyond 10,000 (less common)

That was a mistake

Top 5,000 (fairly common)
Most formal: That was a mistakeMost common: That was a mistake
 I could kill you for thatThat was a mistake
Pronunciation🇬🇧 //aɪ kʊd kɪl juː fə ðæt//🇺🇸 //aɪ kʊd kɪl ju fə ðæt//🇬🇧 //ðæt wəz ə mɪˈsteɪk//🇺🇸 //ðæt wəz ə mɪˈsteɪk//
MeaningI am very angry about what you did.An error or something wrong that was done.
ExampleYou ate my last slice of pizza? I could kill you for that!When I missed the deadline, I knew that was a mistake.
RegisterInformalNeutral
How commonBeyond 10,000 (less common)Top 5,000 (fairly common)
Collocationskill you for that, I could kill you, you've got to be kidding, that was a mistakemake a mistake, admit a mistake, correct a mistake
Common mistakesUsing it in a serious context where it could cause alarm., Misusing it in a light tone with people who may take offense.Using past tense incorrectly, e.g., saying 'That is a mistake' when referring to a past action., Omitting the subject, leading to phrases like 'Was a mistake.', Confusing it with other expressions like 'That was wrong.'
Usage notesThis phrase is often used jokingly among friends but can sound serious. Use cautiously; it may be too aggressive in formal settings."That was a mistake" is often used to acknowledge an error. It's suitable for casual and formal conversations but may be less appropriate in very light-hearted contexts.

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I could kill you for that
That was a mistake

Frequently asked questions: I could kill you for that vs That was a mistake

What's the difference between I could kill you for that and That was a mistake?

I could kill you for that: I am very angry about what you did. That was a mistake: An error or something wrong that was done.

Which is more formal: I could kill you for that and That was a mistake?

That was a mistake is the most formal of these.

Which is more common: I could kill you for that and That was a mistake?

That was a mistake is the most common in everyday English.

Can you show an example of each?

I could kill you for that: You ate my last slice of pizza? I could kill you for that! That was a mistake: When I missed the deadline, I knew that was a mistake.

Can I use I could kill you for that and That was a mistake interchangeably?

Not always. I could kill you for that and That was a mistake 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.