Marginal Propensity to Save

MPS Full Form in English, letter by letter

MPS is Marginal Propensity to Save, the share of each extra rupee of income that a household saves instead of spending.

MPS Full Form in Indian Languages

Economics reduces household behaviour to a few ratios, and the one that starts with S is MPS, the Marginal Propensity to Save. The term is shown below in six Indian languages.

MPS full form and the formula

Marginal Propensity to Save is the share of an extra unit of income that a household saves instead of spending. The formula is MPS = ΔS ÷ ΔY, where ΔS is the change in saving and ΔY is the change in income. If monthly income rises by ₹10,000 and ₹2,500 of that goes into a fixed deposit, MPS is 0.25.

'Marginal' is the key word: it measures a change, not a total. A household may save a tenth of its income on average yet put away half of every bonus. These are two different statistics, and students often mix them up.

MPS, MPC and the multiplier

In the simple Keynesian model MPS + MPC = 1, because every extra rupee is either saved or spent. John Maynard Keynes set out these ideas in The General Theory of Employment, Interest and Money (1936).

The investment multiplier follows from that identity: k = 1 ÷ MPS, which equals 1 ÷ (1 − MPC). With an MPS of 0.25 the multiplier is 4, so ₹1,000 crore of fresh spending can raise national income by about ₹4,000 crore through successive rounds of spending.

A higher MPS weakens the multiplier, because the saved part leaks out of the circular flow of income. The simple formula also assumes no taxes and no imports. In a real economy both are further leakages, so the true multiplier is smaller.

Two worked examples

Example 1. Income rises from ₹50,000 to ₹55,000 and saving rises from ₹7,000 to ₹8,250. The change in saving is ₹1,250 and the change in income is ₹5,000, so MPS = 1,250 ÷ 5,000 = 0.25 and MPC = 0.75. The multiplier is 1 ÷ 0.25 = 4.

Example 2. Suppose MPS is 0.30 and the government spends an extra ₹2,000 crore. The multiplier is 1 ÷ 0.30, about 3.33, so the total rise in income is about ₹2,000 × 3.33 = ₹6,667 crore. The lower the MPS, the larger the total.

MPS and APS: marginal against average

APS, the average propensity to save, is total saving divided by total income over a period. MPS looks only at how saving responds to a change. Someone earning ₹50,000 and saving ₹5,000 has an APS of 0.10, whatever the response to a raise.

APS can be zero or negative when consumption exceeds income, as for students and retirees who draw on past savings. MPS in the usual model lies between 0 and 1, since a household cannot save more than the whole of an extra rupee.

What pushes MPS up or down

Income level comes first. Keynes argued that consumption rises by less than income, so as earnings grow, the share saved tends to grow too. A one-time windfall such as a bonus is usually saved more readily than regular wages.

Life stage matters. Young earners with home loans and school fees save little, mid-career households build reserves for education and weddings, and pensioners draw down savings. Higher interest rates and expected inflation can influence saving, and taxes reduce the income available for either use.

In India, household savings go mostly into bank deposits, gold and real estate, with a smaller share in shares and mutual funds, a pattern shown in Reserve Bank of India surveys. That pattern affects both how the saved money returns to the economy and the returns households earn.

Take a rural household that receives a one-time transfer of ₹3,000. If its MPS is 0.1, it saves ₹300 and spends ₹2,700, and the spending becomes some other household's income. A richer household with an MPS of 0.4 saves ₹1,200 and spends ₹1,800. This is why economists look at who receives money when they estimate how much a stimulus will raise demand, and why the same rupee can have different effects in different hands.

Where MPS turns up in exams and policy

MPS is part of the Class 12 CBSE macroeconomics unit on income determination and appears in economics papers for UPSC and in banking exams, usually as a numerical that gives ΔS and ΔY or asks directly for the multiplier.

In policy it helps judge how far a rupee of spending travels. Tax cuts or transfers to groups with a low MPS, who spend most of what they receive, raise demand faster than cuts for high savers. This is one reason relief for low-income households and farmers is often argued as a way to support demand.

MPS decides how much of an extra rupee stays unspent and how far a rupee of spending travels through the economy. Remember MPS = ΔS ÷ ΔY and k = 1 ÷ MPS, and most exam numericals can be solved from them.

MPS Full Form: Common Questions