About Montematic

What Is This Tool?

Montematic is a free, open-source web application that uses Monte Carlo simulation to help you visualize possible outcomes for your financial future. All calculations run directly in your browser — no data is sent to any server.

Methodology

Simulations use Geometric Brownian Motion (GBM) to model portfolio value over time. Each simulation path applies random returns drawn from a normal distribution with the specified expected return and volatility parameters. Results are aggregated into percentile bands (10th, 25th, 50th, 75th, 90th) for visualization.

The model assumes returns are normally distributed and independent across time periods. Real markets may exhibit fat tails, mean reversion, and other behaviors not captured by this simplified model.

Privacy

This tool runs entirely in your browser. No personal or financial data is collected, stored, or transmitted. Your inputs and results never leave your device.

Disclaimer

This is not financial advice. The results generated by this tool are based on mathematical models and random sampling. They should not be relied upon as predictions of actual future outcomes. Always consult a qualified financial advisor before making investment decisions.