What is Marginal Propensity to Consume (MPC)?

The marginal propensity to consume (MPC), in the economy, is a share of total income or an increase in revenue that consumers tend to spend on goods and services instead of saving. The ratio of total consumption to total income, we know as the average propensity to consume; the increase in consumption caused by the addition of income divided by that increase in income is known as the marginal propensity to consume. Because households divide their income between consumption and savings, the sum of the propensity to spend and the propensity to save will always be equal.


But not all household income spending is on consumption. If the economy is in good condition and most households are in good condition, then a specific portion of households’ income savings. This is necessary, for example, to ensure an acceptable standard of living in periods when current income is insufficient or to generate interest income when the savings portion of income is back to a bank deposit. This means that household income is divided into two parts: spent and saved. This division of income into consumption and savings occurs regardless of what income the household receives – wages, dividends, or rents.

We believe that the average propensity to spend from current income is higher for low-income families than for high-income families. Low-income families, for example, may be forced to give up or borrow only to supply basic necessities, while those exact needs require a much smaller share of high incomes. The average propensity of a low-income family to consume may be greater than one, and a high-income family a fraction of one.

How to calculate MPC

The marginal propensity to spend is equal to the ratio of the change in consumption to the change in income. This is part of the change in consumption per unit of income, which led to them.

MPC = Changes in change in consumption / revenue.


Consumption is a term that refers to the use of natural and produced goods and services to meet personal and collective needs. Man needs a large number of different goods and services to live; the higher the degree of development and civilization, the greater their quantity and diversity. Consumption is the ultimate purpose of all economic activity because both the production and exchange of goods directly or indirectly serve consumption.

However, we should make a distinction between non-productive (real) and productive consumption. Production consumption is an element of production in the consumption of means of production (raw materials, energy, machinery) for production and whose compensation is through the product’s value. The effect of non-production consumption is the maintenance of life comfort and satisfaction. Therefore, production always determines the limits of consumption, not only by the size of the total product but also by deducting the part of the product that serves to maintain the production apparatus, compensating for its worn part and thus maintaining the continuity of production.


Revenue is an increase in economic benefit during the accounting period. Usually in the form of an inflow or an increase in an asset, or a decrease in liability. That is resulting in an increase in equity but not that portion related to payments by equity participants.

Basic income groups:

  • operating income (operating income)
  • income from other activities (financial and other operating income)
  • extraordinary income

They affect the achieved business result of the company, regardless of the cause of their occurrence. They may or may not arise in accordance with the purpose and business objective.

Consumption function

Total consumption consists of autonomous and induced consumption. Induced consumption represents the product of cQ. Then the total consumption (C) can be defined as the sum of Ca (autonomous consumption) and cQ (induced consumption),

 C = Ca + cQ.

We call this equation the consumption function. This shows that autonomous consumption does not depend on changes in Q (national income). We will initially assume that it is constant and, in addition, finds that induced consumption (cQ) changes in proportion to the change in national income ( Q). The coefficient of proportionality is the value of the c – marginal propensity to consume.

Government spending and macroeconomic balance

Total demand is the need of economic agents to purchase a certain amount of goods and services at the current price level in the economy. We have already seen that the private sector does not buy all goods and services. A significant part of GDP is from goods and services financed by the state. Equilibrium in Mixed Strategies. The General Theory of Equilibrium or Walrasian’s General Equilibrium is an attempt to explain the functioning of economic markets as a whole rather than as separate phenomena. Aggregate supply is the number of goods and services in the economy that entrepreneurs offer on the market at a given price level. Commercial bank loans are given not only to private companies and government organizations. Consumer credit also plays an essential role in the active operation of banks.

Good to know

With an increase in income, any person starts spending more on something to save. In practice, everything seems to be quite simple – more money means more than anything else. Economics has many concepts, theories, formulas, and relationships that describe, calculate, and explain this phenomenon. These include the tendency to consume (marginal, average), saving, Keynesian fundamental psychological law, and so on. Knowledge and understanding of economic conditions and the law allow to differently assess common phenomena. As well as the causes and laws that they lead.

Origins, founder and history of Marginal Propensity to Consume

The concept of “marginal propensity to consume and save” emerged in 20-30 years of the last century. He introduced his economic theories to the Englishman John Maynard Keynes. Under consumption includes the use of various goods to meet one person or group of people’s physical, spiritual or individual needs. The savings Keynes determined was the portion of income that was not spent on consumption and was retained to be used in the future to make a better advantage.

The economist also reveals a fundamental psychological law. With the growth of income and consumption necessarily increase in size (expanded range of goods, cheap goods are replaced by more expensive ones, and so on), but not so fast (not proportional). In other words, the more people receive a group of people, the more they spend. But also the more significant amount they have left for savings. Based on his theory, Keynes developed concepts such as the average and marginal propensity to spend (the formula to calculate, too, was withdrawn). Also, the average and marginal propensity to save and the method of calculation. In addition, a reputable economist has identified and established a number of relationships between these concepts.

How to calculate MPC with the multiplier

This connection gives birth to something called the investment multiplier. This is premised on the notion of a positive feedback loop, wherein an increase in average consumer spending ultimately leads to a gain in national revenue larger than the original amount spent at a particular MPC. The connection is:

Multiplier = 1 / 1−MPC

We may use this relationship to calculate how much a nation’s gross domestic product (GDP) will rise over time at a particular MPC, provided all other GDP variables remain constant.

What role does the marginal propensity to consume have in economics?

In Keynesian macroeconomic theory, the marginal willingness to consume is critical in illustrating the multiplier impact of economic stimulus expenditure. Specifically, it indicates that again in government expenditure would raise consumer income, and consumer spending will grow. On a macro level, this rise in investment will contribute to a greater aggregate level of demand.

Example of Marginal Propensity to Consume (MPC)

The Johnson family’s spending in October 2016 was $ 30,000, and in November – $ 35,000. He received revenue in October 2016, when it was equal to $ 40,000, and in November – $ 60,000. Calculate their MPC?

Savings 1 = 40,000 – from 30,000 + 10,000 = dollars.
Savings 2 = 60,000 – 35,000 + 25,000 = dollars.

MPC = Changes in change in consumption / revenue
= 35.000 -30.000 / 60.000 – 40.000
= 0.25


What is MPC?

The marginal propensity to consume (MPC) is defined as the proportion of an aggregate raise in pay that a consumer spends on the consumption of goods and services, as opposed to conserving it.

How to calculate MPC in economics?

The marginal propensity to consume is equal to ΔC / ΔY, where ΔC is the change in consumption, and ΔY is the change in income.

Other calculators

Be sure to check out our MPS Marginal Propensity to Save Calculator to find out what is savings, the function of savings, and how to calculate it. Aso if you are curious about inflation, rising prices…you can read it down in the Factors influencing savings changes part of the calculator.  For more calculators in math, physics, finance, health, and more, visit our CalCon Calculator official page.