What a utility number represents
In economics, utility is a way to model which option someone prefers, not a direct reading of their feelings. A model might assign one bundle of goods a utility of 10 and another a utility of 6 to show that the person ranks the first higher. The numbers make preferences easier to represent and analyze; by themselves, they do not say how happy either choice makes the person.
For many purposes, only the ranking matters. If a model gives the same options values of 100 and 60 instead, it describes the same preference ordering. The scale can be changed without changing the prediction about which option the person favors. That is why comparing utility numbers across different people—or treating a gap between numbers as a measurable amount of satisfaction—usually requires assumptions beyond the numbers themselves.
From preferences to choices
Utility becomes useful when an economist combines it with limits on what a person can choose. A shopper may prefer a larger basket of goods, for example, but a budget rules out baskets that cost too much. The model represents the shopper as choosing the affordable option with the highest utility. It can then help predict how a choice might change if prices or income change.
Economists can also work backward from observed choices. If someone repeatedly chooses one affordable option over another, that pattern can provide evidence about their preferences. But it does not reveal a private sensation directly: the person might have faced constraints the model does not capture, or valued a feature the analyst overlooked.
The practical payoff is a clearer account of tradeoffs. Utility lets a model ask what someone would give up to obtain something they prefer, while keeping the distinction between a structured representation of choice and a measurement of happiness.
