English Idiom – Rule of Thumb.

Meaning – A rough guide or general principle, usually based on experience or practical wisdom. A guideline that is used to make decisions or judgments. This expression is used to refer to an approximate method for doing something, based on experience rather than theory.

It is believed that this phrase is probably based on the use of the thumb as reference for various approximate measurements.

Related Expressions:


When could you use this idiom?

  • When you are explaining to younger people how to take care of things around the house.
  • If you are teaching somebody how to bake a cake and helping them understand general cooking principles.
  • A friend is starting a job at your company, so you are giving them advice on how to fit in.


  • “When deciding how much to save for retirement, a good rule of thumb is to save 10-15% of your income each month.”

In The News:

Updated Rules Of Thumb For Saving For College


  • Is there an idiom like this in your country?

What is an idiom?

An idiom is a word or phrase that is not taken literally.  An idiom is an expression that cannot be understood from the meanings of its individual words, but has a separate meaning of its own.

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