The phrase describes something so expensive that it feels as though it costs a fundamental, irreplaceable part of yourself. It implies not just high cost but excessive cost — more than any reasonable price. A car repair that costs an arm and a leg feels like extortion. A holiday that costs an arm and a leg is one you'll be paying off for months.
The earliest verified uses in print appear in American newspapers and magazines after World War II, from the late 1940s. The phrase is American in origin. One popular explanation — that portrait painters charged more for including the subject's limbs — has not been verified by historical evidence. More likely, the phrase emerged naturally: arms and legs are the most irreplaceable physical things a person possesses, making them the ultimate metaphor for extreme cost.
The phrase is now universal across English-speaking countries. It is used colloquially in speech and informal writing but rarely in formal or professional contexts, where phrases like 'at a significant premium' or 'at considerable expense' are preferred. It remains one of the most recognisable hyperbole phrases in everyday English.
There is no historical evidence that painters charged by the limb. The explanation is plausible-sounding but unverified. The phrase is more likely a natural hyperbole — your limbs being the most precious things you could give.
Yes. German has 'das kostet ein Vermögen' (it costs a fortune). French has 'ça coûte les yeux de la tête' (it costs the eyes from your head). Many languages use body parts as the ultimate currency for describing excessive cost.