how do you calculate marginal propensity to consume 
to calculate the marginal propensity to consume the change in consumption is divided by the change in income for instance if a person s spending increases 90 cents more for each new dollar of earnings it would be expressed as 0 9 1 0 9 on the other hand consider a person receives a bonus of 1 000 and spends 100 of this while saving 900 the marginal propensity to consume would equal 100 1 000 or 0 1 