Open any standard economics textbook, and you will find a neat, tidy graph explaining how companies set their prices. The theory says they search for the exact mathematical point where marginal revenue equals marginal cost. It is an elegant theory—but in the real world of corporate boardrooms, it is almost entirely fictional.

In reality, business managers are rarely sketching out complex marginal cost curves. Instead, they rely on a much simpler, battle-tested strategy: mark-up pricing.

Also known as cost-plus pricing, the concept is straightforward. A business calculates the average total cost of producing a good or service, and then simply adds a percentage premium—the mark-up—on top to guarantee a profit margin. But the fascinating economic question is this: how do companies decide whether to add a 2% mark-up or a 2,000% mark-up?

The answer lies in market power and consumer psychology.

The Supermarket Squeeze

Take a standard UK supermarket. Grocers operate in a ruthlessly competitive market where shoppers will happily cross the street to a rival to save 20p on a tin of baked beans. Because consumers are highly sensitive to price changes (what economists call highly price elastic demand), supermarkets cannot afford large mark-ups. They survive on razor-thin net margins—often as low as 1% to 3%—relying instead on massive economies of scale and rapid inventory turnover. They make pennies per item, but they sell millions of them every single week.

The Brand Illusion

Step into the tech world, and the rules change. Companies like Apple do not price an iPhone based on the raw cost of the glass, battery, and microchips. They price it based on brand loyalty and ecosystem lock-in. Because there are no perfect substitutes for iOS, consumer demand is much more inelastic. This allows tech giants to apply gross mark-ups of 100% or more, capturing huge abnormal profits simply because their brand prestige dictates they can.

The Captive Audience

The most aggressive mark-ups happen when competition drops to absolute zero. Think about buying popcorn at the cinema. Once your ticket is scanned, the venue holds a localized monopoly. You are a captive consumer with no external substitutes. The raw cost of the corn kernels, oil, and the cardboard box is literal pennies, yet a large popcorn routinely sells for over £6. That is a staggering mark-up of around 2,000%.

Ultimately, mark-up pricing proves a vital economic reality. The price tag on a product rarely reflects what it actually costs to manufacture. Instead, it measures exactly how much power a business holds over your wallet.