marginal propensity to save

economics

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July 23, 2026

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In economics, the marginal propensity to save (MPS) is the proportion of an increase in income that consumers save rather than spend. It is calculated as the ratio of a change in saving to a change in income. The MPS is a key concept because it, along with the marginal propensity to consume (MPC), determines how changes in income affect overall economic activity through the multiplier process. The sum of the marginal propensity to save and the marginal propensity to consume always equals one, as any increase in income is either spent or saved.12

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propensity to save
…saving to total income; the marginal propensity to save equals the ratio of a change in saving to a change in income. The sum of the propensity to consume and the propensity to save always equals one (see propensity to consume).
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…saving to total income; the marginal propensity to save equals the ratio of a change in saving to a change in income. The sum of the propensity to consume and the propensity to save always equals one (see propensity to consume).
Read More