Pronunciation: [ɹˈuːl ɒv θˈʌm] (IPA) 
The phrase "rule of thumb" is often used to refer to a practical and approximate guideline rather than a precise measurement. Its origin is debated but one theory suggests it comes from using the thumb as a rough measurement, with the thumb being approximately one inch from the tip to the knuckle. In IPA phonetic transcription, "rule of thumb" would be pronounced /ruːl əv θʌm/.
Rule of thumb is an idiomatic expression that refers to a general practical method or guideline used in everyday situations. Originally derived from the archaic practice of using one's thumb as a rough measurement tool, this phrase now implies a rough estimate or an approximate principle to follow. It denotes a commonsense approach to decision-making or problem-solving without relying on complex calculations or exhaustive analysis.
This conventional rule is considered as a reliable piece of advice or practical wisdom, based on past experience or observation. It typically provides a simplified manner to make predictions, resolve issues, or guide behavior in various domains such as cooking, finance, construction, or personal relationships. Rule of thumb often lacks precision but offers a practical starting point when more precise measurements are unavailable or impractical.
This term is frequently used to describe practical techniques or rules that have stood the test of time and are commonly known among individuals. It can be a mental shortcut or a simplified mnemonic device enabling individuals to quickly assess or evaluate a situation. Although widely accepted, the rule of thumb is not universally applicable and it is important to consider specific circumstances when implementing it.
In summary, rule of thumb is a general practical principle that serves as a quick reference or starting point for decision-making or problem-solving. It is based on common knowledge and is typically employed when exact measurements or analyses are difficult or unnecessary.
