What is the spending multiplier?

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.

What is the marginal propensity to consume (MPC)?

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.

Why is the real multiplier lower than the simple formula suggests?

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.

How does this apply to stimulus checks?

If a government sends out direct payments, the spending multiplier estimates the total GDP impact. With an average MPC of 0.75 and 15% leakages, each $1,400 payment would imply roughly $3,300 in economic activity in this simplified model — but the impact depends heavily on actual consumer spending behavior.

What is a typical spending multiplier in the US?

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.

How does the spending multiplier differ from the money multiplier?

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.

Spending Multiplier Calculator

Free spending multiplier calculator. Compute the Keynesian fiscal multiplier, round-by-round economic impact, and MPC sensitivity analysis with tax and import leakages.

Initial Spending ($)

Marginal Propensity to Consume (MPC)0 to 0.99 — fraction of income spent

Tax Rate (%)Leakage to taxation

Import Leakage (%)Spending that leaves the economy

Savings Leakage (%)

Rounds to Display

Spending Multiplier

2.35

With all leakages

Simple Multiplier

4.00

1 ÷ (1 − MPC)

Total Economic Impact

$2,346.04

$1,000.00 × 2.35

Simple Total Impact

$4,000.00

Without leakages

Effective MPC

0.574

After tax, import, saving leakages

≈ Converges at Round

Spending < 1% of initial

Multiplier Effect Visualization

Initial $1,000.00

Total Impact $2,346.04 (2.3×)

Round-by-Round Spending

Round	New Spending	Cumulative	Cumulative Leaked
1	$1,000.00	$1,000.00	$426.25
2	$573.75	$1,573.75	$670.81
3	$329.19	$1,902.94	$811.13
4	$188.87	$2,091.81	$891.63
5	$108.37	$2,200.18	$937.83
6	$62.17	$2,262.35	$964.33
7	$35.67	$2,298.02	$979.53
8	$20.47	$2,318.49	$988.26
9	$11.74	$2,330.23	$993.26
10	$6.74	$2,336.97	$996.13
11	$3.87	$2,340.84	$997.78
12	$2.22	$2,343.06	$998.73
13	$1.27	$2,344.33	$999.27
14	$0.73	$2,345.06	$999.58
15	$0.42	$2,345.48	$999.76
... 5 more rounds (spending approaches zero)

MPC Sensitivity Analysis

MPC	Simple Multiplier	With Leakages	Total Impact
0.5	2.00×	1.62×	$1,619.43
0.6	2.50×	1.85×	$1,848.43
0.7	3.33×	2.15×	$2,152.85
0.75	4.00×	2.35×	$2,346.04
0.8	5.00×	2.58×	$2,577.32
0.85	6.67×	2.86×	$2,859.19
0.9	10.00×	3.21×	$3,210.27
0.95	20.00×	3.66×	$3,659.65

Planning notes, formulas, and examples

About the Spending Multiplier Calculator

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.

When This Page Helps

Understanding the spending multiplier helps you estimate how stimulus, infrastructure spending, or tax changes ripple through GDP after leakages from taxes, imports, and savings.

How to Use the Inputs

Enter the initial spending injection amount.
Set the marginal propensity to consume (MPC) — the fraction of each dollar that gets re-spent.
Enter the tax rate as a leakage percentage.
Add import leakage (spending that leaves the domestic economy).
Include any savings leakage rate.
Review the multiplier, total impact, and round-by-round table.
Compare different MPC values in the sensitivity table.

Formula used

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)

Example Calculation

Result: Multiplier: 2.35 | Total impact: $2,347

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.

Tips & Best Practices

Higher MPC = larger multiplier — economies where people spend more generate bigger multiplier effects.
Tax cuts have smaller multipliers than direct spending because some of the cut is saved.
The multiplier is largest during recessions when resources are underutilized.
Import leakage is significant in open economies — spending on foreign goods reduces the domestic multiplier.
The round-by-round table shows that most of the multiplier effect occurs in the first 5-8 rounds.

Multiplier in Practice: Government Stimulus

As a historical example, during the pandemic-era U.S. stimulus wave, $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).

Leakages and the Open Economy

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.

Crowding Out: The Multiplier's Limit

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.

Sources & Methodology

Last updated: March 29, 2026

Methodology

This worksheet estimates the simple Keynesian spending multiplier from the entered marginal propensity to consume, then applies the entered tax, import, and savings leakages to derive an effective re-spending rate for the round-by-round table. The total impact is calculated as a geometric-series style multiplier on the initial spending amount, with each round shrinking according to the entered effective leakage assumptions.

The result is a teaching and scenario-planning aid, not an empirical forecast of actual GDP. Real fiscal multipliers vary across business cycles, monetary conditions, and policy design, so the output should be read as a simplified macroeconomic worksheet rather than a prediction of what a specific stimulus program will achieve in practice.

Sources

Principles of Macroeconomics 3e (OpenStax) — Macroeconomics reference for the expenditure multiplier, MPC, and leakage concepts used by the worksheet.
The Budget and Economic Outlook (Congressional Budget Office) — Public reference for the range of fiscal-multiplier estimates discussed in applied policy work.

Frequently Asked Questions

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.