Monte Carlo Retirement Simulator

Each run samples one independent annual nominal return from a normal distribution using the expected return and volatility assumptions. Returns cannot fall below -99.9999%. The annual return is applied as an equivalent monthly rate after each beginning-of-month withdrawal. Spending increases annually with inflation.

The same internal seed makes identical inputs reproducible. Success means every modeled withdrawal through the selected horizon was funded. Percentile balances describe the simulated distribution; they do not predict a particular outcome.

The model excludes taxes, fees, benefits, changing spending, asset-class correlations, fat-tail behavior, and historical return sequencing. Review assumptions and consider professional advice for real retirement decisions.