Keynes defines it as the excess demand in the market for consumption of goods and services. He defined an inflationary gap as an excess of planned expenditure over the available output at pre-inflation or base prices. Given a constant average propensity to save, rising: money incomes at full employment level would lead to an excess of demand over supply and to a consequent inflationary gap. Thus Keynes used the concept of the inflationary gap to show the main determinants that cause an inflationary rise of prices.