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Advanced·8 min read

Future Lab & Monte Carlo

How Luna uses thousands of simulated scenarios to project your financial future and calculate the probability of reaching your goals.

What is a Monte Carlo Simulation?

A Monte Carlo simulation is a mathematical technique that uses random sampling to understand the probability of different outcomes. Named after the famous casino in Monaco, it's the same methodology used by financial advisors, pension funds, and investment firms to model uncertainty.

Instead of predicting a single future (which is impossible), Monte Carlo simulations generate thousands of possible futures based on historical patterns, randomness, and your specific inputs. This gives you a probability distribution of outcomes rather than a false certainty.

How Future Lab Uses Monte Carlo

When you set up a goal in Future Lab, Luna runs 1,000 simulations of your financial future. Each simulation considers:

Income Variability

Your income may fluctuate due to bonuses, job changes, or economic conditions. Each simulation applies random variations within historical patterns.

Market Returns

Investment returns are inherently unpredictable. We model market volatility using historical return distributions, including rare but impactful events.

Spending Patterns

Your actual spending varies month-to-month. Simulations account for this natural variability rather than assuming perfect consistency.

Inflation

The purchasing power of money changes over time. Each simulation applies realistic inflation scenarios to both your savings and future expenses.

Understanding Your Success Rate

After running 1,000 simulations, Luna counts how many scenarios achieved your goal. If 780 out of 1,000 simulations succeeded, your success rate is 78%.

90%+

Very High Confidence

70-89%

Good Trajectory

<70%

Consider Adjustments

A 78% success rate doesn't mean you have a 78% chance of success—it means that in 78% of the simulated scenarios, given the range of possible outcomes, you achieved your goal. This is more nuanced and honest than a single-point prediction.

The Projection Range

Future Lab shows you three scenarios from the simulation results:

Optimistic (90th percentile)— Things go better than expected
Expected (50th percentile)— The most likely outcome
Conservative (10th percentile)— A "bad luck" scenario

Planning for the conservative scenario while hoping for the optimistic one is a prudent approach to financial goal-setting.

Improving Your Success Rate

If your success rate is lower than you'd like, Future Lab lets you experiment with different scenarios:

Increase contributionsEven small increases compound significantly over time

Extend your timelineMore time allows for recovery from market downturns

Reduce the goal amountA smaller target is easier to hit with high confidence

Adjust risk toleranceDifferent investment strategies affect the range of outcomes

Important: The projections shown in Future Lab are hypothetical and based on the information you've entered. They are not predictions of actual performance and should not be considered financial advice. All investing involves risk, including the potential loss of principal. Past performance does not guarantee future results. Consult a qualified financial advisor before making investment decisions.

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Disclaimer: The content, tools, and resources on Luna Money are intended solely for informational and educational purposes and should not be construed as professional financial, investment, or tax advice. Our materials are designed to provide general guidance and are based on the input and data provided by users. Luna Money makes no guarantee of the accuracy, completeness, or applicability of this content to individual circumstances. The Safe-to-Spend calculations, budgets, and insights provided are estimates only. We strongly recommend consulting a qualified financial professional who can provide personalized advice based on your unique financial situation before making any significant financial decisions. Luna Money is not a bank and does not hold funds. Bank connections are securely handled through Plaid. All content and tools on Luna Money are provided without any guarantees or warranties of any kind.