According to the law of diminishing marginal utility, as the amount of a good consumed increases, the marginal utility of that good tends to

The Law of Diminishing Marginal Utility is a fundamental principle in consumer theory which states that as a consumer increases the consumption of a specific commodity, the marginal utility (MU) derived from each additional unit declines [2]. Marginal utility represents the change in total utility resulting from a one-unit increase in consumption [1]. Initially, total utility increases, but it does so at a diminishing rate because the consumer's desire for the product weakens as they obtain more of it [2]. Eventually, the marginal utility may reach zero (satiation point) or even become negative if further consumption becomes unfavorable. This downward trend in marginal utility explains why consumers are typically willing to pay less for subsequent units of a good, leading to the negative slope of the demand curve [3].

Sources

1. [1] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > Table 2.1: Values of marginal and total utility derived from consumption of various amounts of a commodity > p. 10
2. [2] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > Measures of Utility > p. 9
3. [3] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > Derivation of Demand Curve in the Case of a Single Commodity (Law of Diminishing Marginal Utility) > p. 11