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Marginal Propensity to Consume Calculator

Calculate Marginal Propensity to Consume (MPC), Marginal Propensity to Save (MPS), and the Keynesian spending multiplier from changes in income and consumption.

Income and spending

$
$
$
$

Marginal propensity to consume (MPC)

0.7500

75.0% of incremental income is spent

Marginal propensity to save (MPS)

0.2500

25.0% saved

Spending multiplier

4.00x

1 ÷ MPS

Change in income (ΔY)

$10,000.00

Change in consumption (ΔC)

$7,500.00

Change in savings (ΔS)

$2,500.00

Incremental income allocation

  • Consumption$7,500.0075.0%
  • Savings$2,500.0025.0%
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Marginal propensity to consume and the spending multiplier

Marginal propensity to consume (MPC) measures what fraction of an additional dollar of income households spend rather than save. It is a core concept in Keynesian macroeconomics: higher MPC means more of each income boost circulates through the economy, amplifying demand through the spending multiplier.

Enter before-and-after income and consumption levels, or supply the direct changes (ΔY and ΔC). The calculator returns MPC, marginal propensity to save (MPS), the multiplier, and the implied change in savings. For the savings-side view, use the marginal propensity to save calculator. For related elasticity concepts, see the income elasticity of demand calculator and the consumer surplus calculator.

MPC and multiplier formulas

MPC=ΔCΔY\mathrm{MPC} = \frac{\Delta C}{\Delta Y}
MPS=1−MPC\mathrm{MPS} = 1 - \mathrm{MPC}
Multiplier=11−MPC=1MPS\text{Multiplier} = \frac{1}{1 - \mathrm{MPC}} = \frac{1}{\mathrm{MPS}}

MPC plus MPS always equals 1 for a closed economy with no taxes or imports in the simplest model. The multiplier shows how much total spending rises when autonomous spending increases by one dollar.

Worked example

Income rises from $50,000 to $60,000 while consumption increases from $40,000 to $47,500. ΔY = $10,000 and ΔC = $7,500, so MPC = 0.75. MPS = 0.25 and the multiplier = 1 ÷ 0.25 = 4. Each $1 of new spending could generate $4 of total economic activity in this simplified framework.

Frequently asked questions

What is a typical MPC for U.S. households?
Empirical estimates vary by income bracket and time period. Lower-income households often show higher MPC because more of each dollar covers necessities. Aggregate MPC is frequently estimated between 0.6 and 0.9 in short-run studies.
Can MPC be greater than 1?
In basic theory, MPC should fall between 0 and 1. Values above 1 would imply households spend more than the entire income increase, typically financed by borrowing. Sustained MPC above 1 is unusual in aggregate data.
How does MPC relate to fiscal stimulus?
Government transfers or tax cuts have larger demand effects when recipients have high MPC. Economists use MPC and multiplier estimates to project GDP impact from stimulus programs.
What is the difference between MPC and average propensity to consume?
Average propensity to consume is total consumption divided by total income. MPC measures only the response to an incremental change in income, which is what drives the multiplier.

Resources and references

The formulas and methods in this calculator were checked against these independent sources.