Marginal Propensity to Consume

What is this formula?

Marginal Propensity to Consume measures the fraction of an additional unit of disposable income that is spent on consumption.

It shows how household consumption changes when income increases or decreases.

When to use it

Use this formula when analyzing consumer behavior, fiscal policy effects, Keynesian multipliers, and changes in aggregate demand.

Example

Initial disposable income:

Y1 = 2000 USD

Final disposable income:

Y2 = 2500 USD

Initial consumption:

C1 = 1600 USD

Final consumption:

C2 = 1950 USD

Formula:

MPC = (C2−C1)/(Y2−Y1)

Substitution:

MPC = (1950−1600)/(2500−2000)

MPC = 350/500

MPC = 0.70

Result:

Households spend 70% of each additional unit of disposable income on consumption.

Applications

- Keynesian multiplier analysis

- Fiscal policy evaluation

- Household consumption studies

- Aggregate demand forecasting

- Macroeconomic education

Note

This formula estimates MPC over a finite income interval. In practice, the marginal propensity to consume may vary by income level, household type, economic conditions, and expectations about future income.