What does 'it costs an arm and a leg' mean?

What it means: Very expensive - so expensive that it feels like an unreasonable price. "This car cost an arm and a leg" means the car was outrageously priced.

Why this phrase: The idea is that the price is so high it's as if you'd have to give up a limb to pay it - your most valuable physical possessions. There's no single agreed origin, though it became widespread in American English after World War II.

• "Childcare costs an arm and a leg in this city."
• "I'd love to go to Japan, but flights cost an arm and a leg."
• "The repairs didn't cost an arm and a leg - surprisingly reasonable."

The key: It's always about price being high. It doesn't work for other kinds of sacrifice.

• "It's very expensive" - neutral and clear
• "It cost a fortune" - very common informal alternative
• "It's pricey" - softer criticism of price
• "It'll set you back..." - "That'll set you back £500" is a natural way to mention a high price
• "It's highway robbery" - specifically about prices that feel unfairly inflated

Register: Casual. Works in everyday conversation. Too informal for formal writing.

Tags: idiom, money, price, everyday English, informal