Marginal propensity to consume

In economics, the marginal propensity to consume (MPC) is a metric that quantifies induced consumption, the concept that the increase in personal consumer spending (consumption) occurs with an increase in disposable income (income after taxes and transfers). The proportion of disposable income which individuals spend on consumption is known as propensity to consume. MPC is the proportion of additional income that an individual consumes. For example, if a household earns one extra dollar of disposable income, and the marginal propensity to consume is 0.65, then of that dollar, the household will spend 65 cents and save 36 cents. Obviously, the household cannot spend more than the extra dollar (without borrowing).

According to John Maynard Keynes, marginal propensity to consume is less than one.

Mathematically, the ${\displaystyle {\mathit {MPC}}}$ function is expressed as the derivative of the consumption function ${\displaystyle C}$ with respect to disposable income ${\displaystyle Y}$, i.e., the instantaneous slope of the ${\displaystyle C}$-${\displaystyle Y}$ curve.

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