Idiom:  don't judge a book by its cover

Book cover with a microphone image and the sentence example, Susan Boyle showed the judges on Britain's Got Talent why you shouldn't judge a book by its cover.


Idiom:  (you can’t/never/don't) judge a book by its cover

  • it's not good to decide about something based on its outward appearance only

Note:  In book publishing, an enormous amount of attention is put into the design of a book's cover because most people will not carefully read through the book before making a purchase. As a result, the cover of a book often does not closely match the book's contents.

Example sentences

  • In Los Angeles, you can’t judge a book by its cover because some of the richest people shop in jeans and a T-shirt.
  • Wow, chocolate-covered crickets are really delicious. It just shows that you can't judge a book by its cover.
  • Try to keep an open mind about the new software updates.  It's never a good idea to judge a book by its cover.
  • He seems really short to be a basketball player but after two decades coaching, I've learned to not judge a book by its cover.
  • Marketers know very well that consumers will judge a book by its cover and this is why even the cheapest cosmetics come in attractive packaging.
  • Fortunately, one of the valuable lessons my parents taught me was never to judge a book by its cover.
  • If I'd judged a book by it's cover, I'd never have married the love of my life.
  • When Susan Boyle sang on Britain's Got Talent, she proved that you can't judge a book by its cover.

By the way, if you've never seen Susan Boyle's audition for Britain's Got Talent, you should watch it below!


  • all that glitters is not gold
  • looks can be deceiving

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