What does "cost an arm and a leg" mean?

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. The phrase carries a note of complaint or surprise, so you use it when a price feels shocking rather than merely a bit high. If a coffee costs a little more than you expected, you would not reach for this idiom. But if a plumber hands you a bill three times what you imagined, "it cost an arm and a leg" fits perfectly.

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. Some people link it to soldiers who lost limbs in the war, suggesting that certain things cost you dearly, but this is folk etymology rather than proven history. What matters for learners is the vivid image: you are exaggerating on purpose to show how painful the price feels.

• "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."
• "Wedding venues these days cost an arm and a leg."
• "Don't buy the brand name, it costs an arm and a leg for the same thing."

It's always about price being high. It doesn't work for other kinds of sacrifice. If something demands a lot of effort, time, or emotional energy, you need a different expression. For those situations, English speakers might say "it took a lot out of me" or "it was a real struggle." Reserve "an arm and a leg" strictly for money.

Learners sometimes change the body parts or the number, saying "it cost an arm and a foot" or "it costs arms and legs." The phrase is fixed. It is always "an arm and a leg," singular, in that exact order. Swapping the words makes it sound broken to a native ear.

Picture yourself at a checkout being asked to literally hand over your arm and your leg to pay. The image is absurd and painful, and that absurd pain is exactly the feeling the idiom expresses. If the price does not make you wince, the phrase does not apply.

• "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

Both British and American speakers use "it costs an arm and a leg" freely, so this one travels well. A small difference appears in the alternatives. British speakers often say something "cost a bomb," as in "That holiday cost a bomb," which sounds natural in the UK but can puzzle Americans. Americans are more likely to say something "cost a pretty penny."

In casual conversation with friends, this idiom is completely at home. In a professional email or a report, choose "expensive" or "the cost is significant" instead. You might still hear it in a relaxed office chat, for example "The new software licence costs an arm and a leg," but keep it out of anything you would want to sound polished and formal.

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