Let the cat out of the bag
/let ðə kæt aʊt əv ðə bæɡ/informalUK · US
What does “Let the cat out of the bag” mean?
Let the cat out of the bag means to reveal a secret, usually by accident.
The difference from "spill the beans" is intent: letting the cat out of the bag is usually a slip, while spilling the beans is often deliberate.
It is friendly and slightly forgiving in tone.
When do people say it?
Used when a surprise or confidence is given away unintentionally.
“He let the cat out of the bag about the engagement before they'd told her parents.”
Is it formal or informal?
Register: informal. It is most at home in everyday conversation rather than formal writing. Most common in UK and US.
Where does it come from?
In English from the eighteenth century; the market-fraud explanation is traditional but unproven.
Origin confidence: Disputed; treat with caution
How do you say “Let the cat out of the bag” in other languages?
Related idioms
- Spill the beans, To give away a secret.
Last reviewed 2026-09-11