When something costs an arm and a leg, it's not just pricey. It's outrageously, groan-worthily expensive. The idiom appears in casual conversation, in product reviews, in newspaper headlines. Yet almost nobody stops to ask why losing two limbs became English's go-to image for a steep price. The answer is more interesting than most people expect, and the phrase itself is more flexible than it first appears.
What "costs an arm and a leg" means
The phrase means that something costs a very large or unreasonable amount of money. It's hyperbolic: you aren't literally sacrificing limbs, but the exaggeration makes the point sharply. A car repair that wipes out three months of savings costs an arm and a leg. So does a concert ticket bought at the last minute, or a two-bedroom flat in central London.
The idiom always carries a note of complaint or disbelief. It's not neutral. Saying something "costs an arm and a leg" signals that the speaker considers the price excessive, even offensive. That emotional charge is what separates it from simply saying "it's expensive."
Where the phrase comes from
The origin is disputed, and anyone who tells you they know for certain is guessing. Two popular theories circulate, and both are plausible.
The first links the phrase to portrait painting. In the 18th and early 19th centuries, artists charged by the number of body parts they included. A head-and-shoulders portrait cost less than a full-length one showing hands, legs, and feet. Clients who wanted the whole picture paid considerably more. Historians have found no direct evidence tying this practice to the exact phrase, but the economic logic is sound.
The second theory connects the idiom to war. Soldiers who lost limbs in combat paid the highest possible price. The idea that something of enormous cost demands a limb as payment appears in American English from the 1940s onward. The earliest printed uses cluster around that period: the phrase appears in the San Francisco Examiner in 1949 and in other American newspapers shortly after. This timing fits the post-World War II era, when the cost of things, and the cost of war, were both fresh in public consciousness.
Neither theory is confirmed. What's clear is that the phrase is American in origin and didn't appear in print much before the mid-20th century.
How to use it in a sentence
The phrase is idiomatic, so it works best in informal or conversational registers. It fits spoken English, personal essays, journalism, and social media. It sits awkwardly in formal reports or academic writing.
A few things to keep in mind. The phrase is almost always used in the third person ("it costs an arm and a leg") rather than first-person direct statements. It works with past tense too: "the renovation cost us an arm and a leg." You can also use it attributively before a noun, though that's less common: "arm-and-a-leg prices."
Here are some natural examples:
- "Getting the boiler replaced cost an arm and a leg, but we had no choice."
- "You don't have to spend an arm and a leg on a decent espresso machine."
- "Childcare in this city costs an arm and a leg."
Notice that each sentence carries a mild grievance. That tone is part of the phrase's meaning. Drop it into a neutral factual sentence and it creates a jarring register mismatch.
Variations and related expressions
English has a cluster of idioms for high prices, and "costs an arm and a leg" sits at the dramatic end of the scale. "Doesn't come cheap" is milder. "Will set you back a pretty penny" is older and slightly more playful. "Cost a fortune" is vaguer but widely understood.
Some speakers extend the arm-and-leg phrase for comic effect: "it cost an arm, a leg, and my firstborn." That's informal wordplay, not standard usage, but it shows how the idiom lends itself to exaggeration.
If you're biting the bullet and paying the high price anyway, you might use both idioms in the same sentence: "It costs an arm and a leg, but we bit the bullet." The two phrases pair naturally because both describe enduring something unpleasant.
Common mistakes when using the phrase
The most frequent error is mixing the tense of "cost." The verb here is irregular: it's "cost an arm and a leg" in the present, and "cost an arm and a leg" in the past too. There's no "costed." Writers sometimes reach for "costed" by analogy with regular verbs, but it doesn't exist in standard English.
A subtler mistake is using the phrase for things that are merely moderately expensive. The idiom implies real shock. If you describe a five-dollar coffee as costing an arm and a leg, the hyperbole falls flat because the gap between the image and the reality is too small to be funny or meaningful. Save the phrase for genuine sticker shock.
It's also worth knowing when to avoid the idiom entirely. In a cover letter, a business proposal, or a formal complaint, the phrase reads as too casual. Opt for "at significant cost," "prohibitively expensive," or simply the actual number.
Why the phrase works so well
Idioms earn their place in a language by doing something that literal language can't. "Costs an arm and a leg" compresses a complaint, an expression of disbelief, and a social signal into six words. The listener understands not just that the price is high, but that the speaker finds it unreasonable and wants sympathy.
The body-part imagery helps. Limbs are visceral. Invoking them makes the cost feel physical, like the price is extracting something from you. That's a much stronger image than "very expensive," and it's why the phrase has survived for more than 70 years without fading.
Like sitting on the fence, "costs an arm and a leg" works because the image is instantly legible. You don't need to unpack it. You hear it and you know exactly what it means and how the speaker feels about it. That's the mark of an idiom doing its job.