Rule of thumb

Meaning

A general principle or guideline that is followed because it works in most situations, rather than a scientific or rigid law. It is a handy shortcut for estimation.

Practical, common-sense

Used in a sentence

• A good rule of thumb is to allow one pound of turkey per person for dinner.
• My rule of thumb is never to bet money you cannot afford to lose.
• What is your rule of thumb for how long to keep tax returns?