Free spending multiplier calculator. Compute the Keynesian fiscal multiplier, round-by-round economic impact, and MPC sensitivity analysis with tax and import leakages.
The Spending Multiplier Calculator computes the total economic impact of an initial injection of spending using the Keynesian fiscal multiplier. Enter the initial spending, marginal propensity to consume (MPC), and leakages (taxation, imports, savings) to see how spending ripples through the economy round by round.
The spending multiplier is a cornerstone of Keynesian economics. When someone spends $1,000, the recipient saves some and spends the rest. That spending becomes income for someone else, who spends a portion, and so on. With an MPC of 0.75, $1,000 eventually generates $4,000 in total economic activity. But real-world leakages — taxes, imports, and savings — reduce this multiplier significantly.
The round-by-round table shows exactly how the initial spending cascades through the economy, while the MPC sensitivity analysis reveals how small changes in consumer spending behavior dramatically affect the total economic impact. This is essential for understanding the impact of government stimulus, infrastructure spending, and tax policy.
Understanding the spending multiplier is essential for economics students, policy analysts, and anyone evaluating the impact of government spending programs or stimulus checks on the broader economy. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
Simple Multiplier = 1 ÷ (1 − MPC) Effective MPC = MPC × (1 − Tax Rate) × (1 − Import Rate) − Savings Rate Complex Multiplier = 1 ÷ (1 − Effective MPC) Total Impact = Initial Spending × Multiplier Round n Spending = Initial × (Effective MPC)^(n−1)
Result: Multiplier: 2.46 | Total impact: $2,460
Effective MPC: 0.75 × 0.85 × 0.90 = 0.574. Multiplier: 1 ÷ (1 − 0.574) = 2.35. $1,000 initial spending generates $2,347 total economic activity. Converges around round 12.
During the 2020-2021 COVID stimulus, $5.2 trillion was injected into the US economy. With an estimated MPC of 0.6-0.8 for recipients, the spending multiplier ranged from 1.5 to 2.5. Direct payments ($1,200-$1,400) had lower multipliers (recipients saved much of it), while unemployment benefits had higher multipliers (recipients spent most of it immediately).
In highly open economies (small countries with high imports), the spending multiplier can be less than 1 — meaning government spending generates less total domestic GDP than the amount spent. For example, Singapore with ~180% trade-to-GDP ratio sees significant import leakage, reducing fiscal multipliers.
In full-employment economies, government spending may "crowd out" private investment by raising interest rates, reducing the effective multiplier. This is why the multiplier is typically larger during recessions and smaller during booms — the marginal productivity of additional spending depends on how much slack exists in the economy.
The spending multiplier shows how an initial injection of spending creates a larger total economic impact through successive rounds of consumer spending. A multiplier of 3 means $1 of new spending generates $3 of total GDP impact.
MPC is the fraction of each additional dollar of income that consumers spend rather than save. An MPC of 0.8 means 80 cents of each dollar received is spent, creating the next round of the multiplier effect.
Leakages reduce the effective MPC at each round: taxation removes spending power, imports send money abroad, and savings remove money from circulation. A simple MPC of 0.75 might have an effective MPC of 0.55 after leakages.
When the government issues $1,400 stimulus checks, the spending multiplier estimates total GDP impact. If average MPC is 0.75 with 15% leakages, each $1,400 generates ~$3,300 in economic activity — but the impact depends heavily on actual consumer spending behavior.
Empirical estimates range from 0.5 to 2.5 depending on economic conditions. The multiplier is higher during recessions (more idle resources to activate) and lower during full employment. Government infrastructure spending typically has multipliers of 1.5-2.0.
The spending multiplier applies to real economic spending and GDP impact. The money multiplier applies to the banking system, showing how deposits create new money through lending. They are related but distinct concepts.