If you’re learning English, let the cat out of the bag is a common idiom worth knowing. It means to reveal a secret or private information, often accidentally or before the right time.
The phrase appears in everyday American English, especially when people discuss surprises, plans, announcements, or private news. This guide explains its meaning, grammar, pronunciation, examples, synonyms, common mistakes, and uncertain historical origin.
Quick Answer
Let the cat out of the bag means to reveal a secret, often by accident or too early.
Example: “I let the cat out of the bag about the surprise party.”
TL;DR
• It means revealing information that was meant to stay secret.
• Accidental disclosure is a common use.
• The phrase is informal and conversational.
• “The cat is out of the bag” describes the result.
• “Spill the beans” is a close informal alternative.
• The phrase’s exact origin remains uncertain.
Meaning of Let the Cat Out of the Bag
Let the cat out of the bag means to reveal something that was supposed to remain secret.
Cambridge defines the idiom as allowing a secret to become known, usually without intending to. Collins similarly describes it as revealing something secret or private.
The phrase can describe a small slip or a major disclosure. The key idea is that hidden information becomes known.
• “Mia let the cat out of the bag about the birthday surprise.”
• “Don’t let the cat out of the bag before Saturday.”
• “Who let the cat out of the bag?”
How to Use the Idiom in a Sentence
Use this idiom when someone reveals information that should have remained private.
It works especially well in conversations about surprises, plans, gifts, announcements, and personal news. It is normally used figuratively, not literally.
Common patterns include:
• Subject + let + the cat out of the bag: “Jake let the cat out of the bag.”
• Negative command: “Don’t let the cat out of the bag.”
• Question: “Who let the cat out of the bag?”
• With about + information: “She let the cat out of the bag about the new project.”
Let the Cat Out of the Bag Examples
The idiom sounds most natural when the reader knows there was information to keep secret.
These original examples show several everyday situations.
• Surprise: “Ben let the cat out of the bag about the surprise dinner.”
• Gift: “I nearly let the cat out of the bag about her present.”
• Travel: “My sister let the cat out of the bag about our weekend trip.”
• Work: “Someone let the cat out of the bag about the new office.”
• Announcement: “The company accidentally let the cat out of the bag.”
• Family: “Dad let the cat out of the bag during breakfast.”
• School: “I let the cat out of the bag about the class celebration.”
• Conversation: “She let the cat out of the bag without realizing it.”
How to Pronounce “Let the Cat Out of the Bag”
A simple learner-friendly pronunciation is approximately “let thuh cat out uhv thuh bag.”
The words should flow naturally rather than being pronounced as separate, strongly stressed words.
The key words usually receive more attention in normal speech:
• let
• cat
• out
• bag
Wiktionary lists the phrase as an idiomatic verb expression and records its related verb forms.
What Does “The Cat Is Out of the Bag” Mean?
The cat is out of the bag means the secret is already known.
This form focuses on the situation after the disclosure. Let the cat out of the bag focuses on the action that revealed it.
• Action: “Lisa let the cat out of the bag.”
• Result: “Now the cat is out of the bag.”
• Action: “Someone let the cat out of the bag yesterday.”
• Result: “The cat is already out of the bag.”
This distinction helps English learners choose the right form.
Is “Let the Cat Out of the Bag” Informal?
Yes. Let the cat out of the bag is generally an informal English idiom.
It sounds natural in conversations, messages, casual stories, and other everyday situations. Collins lists the expression in American English and describes it as revealing something secret or private.
For formal writing, choose a direct alternative when appropriate:
• Informal: “She let the cat out of the bag.”
• Neutral: “She revealed the information.”
• Formal: “She disclosed the information.”
Let the Cat Out of the Bag vs. Spill the Beans
Let the cat out of the bag and spill the beans both describe revealing a secret.
They are close in meaning, but they aren’t identical in every situation. Both are common informal expressions.
| Expression | Main idea | Example |
|---|---|---|
| Let the cat out of the bag | Reveal hidden information | “He let the cat out of the bag.” |
| Spill the beans | Reveal a secret | “She spilled the beans.” |
| Reveal a secret | State the meaning directly | “She revealed the secret.” |
| Let slip | Reveal something accidentally | “He let the news slip.” |
Spill the beans often sounds playful. Reveal and disclose are more direct and neutral.
Synonyms for Let the Cat Out of the Bag
The best synonym depends on the situation and level of formality.
Some alternatives preserve the informal tone, while others sound more professional.
• Reveal a secret — neutral and direct.
• Disclose information — formal and precise.
• Give something away — conversational.
• Let something slip — often suggests an accidental disclosure.
• Spill the beans — informal and playful.
• Tell the secret — very direct.
• Make something known — neutral.
• Divulge information — formal and less conversational.
• Give away the surprise — useful for planned surprises.
• Break the news — useful when revealing important news.
Common Sentence Patterns
The idiom has a fixed structure, but the verb can change with the subject and tense.
These patterns cover most everyday uses.
• I let the cat out of the bag.
• She lets the cat out of the bag.
• He let the cat out of the bag yesterday.
• They are letting the cat out of the bag.
• Don’t let the cat out of the bag.
• Who let the cat out of the bag?
• Nobody should let the cat out of the bag.
• I almost let the cat out of the bag.
Verb Forms and Tense Usage
The verb let is unusual because its simple present base form and simple past form are both let.
Only the third-person singular present uses lets. The continuous form is letting.
• Present: “I let the cat out of the bag.”
• Third-person present: “She lets the cat out of the bag.”
• Past: “She let the cat out of the bag.”
• Present continuous: “He is letting the cat out of the bag.”
• Infinitive: “Try not to let the cat out of the bag.”
A common mistake is changing the past form to letted. The correct past form is let.
Common Mistakes to Avoid
Most mistakes involve changing the fixed wording or using the phrase outside its usual meaning.
Keep these points in mind:
• Correct: “She let the cat out of the bag.”
• Incorrect: “She let the cat outside of the bag.”
• Correct: “He let the cat out of the bag yesterday.”
• Incorrect: “He lets the cat out of the bag yesterday.”
• Correct: “She lets the cat out of the bag.”
• Incorrect: “She letted the cat out of the bag.”
• Use the idiom when something was hidden or private.
• Don’t use it simply to mean “talk.”
• Remember that let is also the simple past form.
• Use the cat is out of the bag when the secret has already become known.
Can You Use It for Intentional Secrets?
Yes. The idiom often suggests accidental or careless disclosure, but the context can also describe an intentional reveal.
For example, a person might deliberately reveal a secret after deciding it should no longer remain private.
• Accidental: “I didn’t mean to let the cat out of the bag.”
• Careless: “He let the cat out of the bag during the meeting.”
• Intentional: “She decided to let the cat out of the bag and explain the plan.”
The important idea is revealing something that had previously been hidden.
Origin of Let the Cat Out of the Bag
The exact origin of let the cat out of the bag is not certain.
A popular explanation connects the phrase with an old market story. According to the story, a dishonest seller supposedly substituted a cat for a piglet inside a bag. Opening the bag exposed the deception.
Another theory connects the “cat” with the cat o’ nine tails, a historical whip. However, the evidence for this explanation is weak.
The safest explanation is therefore simple: the phrase’s exact origin is uncertain, although several theories have been proposed.
Is the Origin of the Idiom Known?
The historical record gives us more confidence about the phrase’s use than its original story.
Phrase Finder identifies a 1760 printed example in The London Magazine. The expression was already being used to describe revealing something that should have remained hidden.
That evidence is useful because it separates two questions:
• When do we have documented evidence of the phrase? At least by 1760 in the cited printed record.
• Why was a cat placed in a bag? The exact answer remains uncertain.
The popular pig-in-a-poke explanation is memorable, but it should be treated as a theory rather than proven history.
American English Usage
Let the cat out of the bag is a natural expression in American English.
Americans may use it when discussing surprises, private information, plans, gifts, promotions, trips, or announcements. Collins specifically provides an American English definition for the expression.
• “Don’t let the cat out of the bag about the party.”
• “My brother let the cat out of the bag.”
• “Who let the cat out of the bag?”
For professional or formal communication, reveal, disclose, or announce may be clearer.
Let the Cat Out of the Bag in Conversation
The idiom is especially natural in short conversations.
It can express surprise, disappointment, humor, or mild frustration when someone reveals information too soon.
A: “Why does everyone know about the party?”
B: “Sorry. I think I let the cat out of the bag.”
A: “You weren’t supposed to tell anyone!”
This kind of dialogue shows why the idiom often has a conversational and slightly playful tone.
Practice Sentences and Quick Tips
Use these tips when writing or speaking.
• Use the phrase when a secret becomes known.
• Use it for surprises that someone reveals too early.
• Use the cat is out of the bag for the resulting situation.
• Use spill the beans as a similar informal expression.
• Use reveal for a neutral alternative.
• Use disclose when a formal tone fits.
• Remember that the past form of let is also let.
• Add about when naming the secret: “She let the cat out of the bag about the trip.”
FAQs
What does “let the cat out of the bag” mean?
It means to reveal a secret or private information. The disclosure is often accidental, careless, or earlier than intended.
Is “let the cat out of the bag” an idiom?
Yes. It is an English idiom whose figurative meaning is different from the literal words.
What is another way to say “let the cat out of the bag”?
You can say reveal a secret, give something away, let something slip, or disclose information. Spill the beans is a similar informal idiom.
Is “let the cat out of the bag” formal?
It is generally informal. In formal writing, reveal or disclose may be a better choice.
What is the difference between “let the cat out of the bag” and “the cat is out of the bag”?
The first describes revealing the secret. The second describes the situation after the secret has become known.
Can you use the phrase for an intentional reveal?
Yes. Accidental disclosure is common, but context can show that the revelation was deliberate.
Is the origin of “let the cat out of the bag” known?
Not with certainty. The popular market story is widely repeated, but the exact origin remains uncertain.
Conclusion
Let the cat out of the bag means to reveal information that was supposed to stay secret. It is a common informal expression in American English and works well for surprises, plans, announcements, and private news.
Remember the key distinction: let the cat out of the bag describes the action, while the cat is out of the bag describes the result. Try writing three original sentences with the idiom to make the expression part of your everyday English.