Rule of thumb

The phrase "Rule of thumb" is an idiom that means a generally reliable and easy-to-remember principle or guideline that can be applied in various situations without needing to be precise or exact. It typically refers to a practical and convenient rule that serves as a rough estimate or method for making decisions or judgments. The origins of the phrase are often attributed to an old English law that allowed a man to beat his wife with a stick no wider than his thumb, although this historical association is debated. In modern usage, the term "Rule of thumb" has no connection to violence and is primarily used to describe a practical rule or guideline.