Definition of rule of thumb in US English:

rule of thumb


  • A broadly accurate guide or principle, based on experience or practice rather than theory.

    • ‘A widely adopted rule of thumb in crystallisation theory is that better crystals can be obtained using programmed cooling.’
    • ‘Observation of individuals shows that people are much more likely to use rules of thumb when making complex decisions.’
    • ‘As a rule of thumb, allow one houseplant per 100 square feet of living area.’
    • ‘I want to suggest that this is in fact a rather useful rule of thumb for linguists and philologists.’
    • ‘As a rough rule of thumb, the best rates are available either over the internet or from some of the aggressive building societies.’
    • ‘A good rule of thumb would be to use colors based upon the type of effect you're trying to achieve.’
    • ‘The general rules of thumb for a good private detective, Eddie said, are to be able to blend in, to act normally and be discreet.’
    • ‘Given that forecasts were so inaccurate, I thought it might be preferable to rely on projections based on simple rules of thumb.’
    • ‘This is a good rule of thumb, and the first principle we use in evaluating potential home remedies.’
    • ‘The rule of thumb usually is to have three days of food and water and whatever essentials you might have.’