How to calculate the spending multiplier in an economy?

To calculate the spending multiplier in an economy, you can use the formula: Spending Multiplier 1 / (1 - Marginal Propensity to Consume). The Marginal Propensity to Consume is the proportion of additional income that people spend rather than save. By plugging in the value for the Marginal Propensity to Consume, you can determine the overall impact of an initial change in spending on the economy.