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🧓 Retirement Portfolio Monte Carlo

A 3D Monte Carlo simulation of a retirement portfolio: drag the chart's own handles or use the sliders to set contributions, market volatility, withdrawal rate and retirement age, then watch hundreds of possible futures play out and the risk of running out of money.

Financial Models & Markets2DModerate60 FPS

A 3D Monte Carlo simulation of compound growth and retirement withdrawals: hundreds of random market paths run at once, so you can see the spread of possible outcomes and the risk of running out of money — not just one lucky average.

🔬 How it works

Each year the balance grows by B(t+1) = B(t)·(1+r_t) + C before retirement, where r_t = μ + σ·Z_t is drawn from a normal distribution (Box–Muller). After retirement, a percentage withdrawal W(t) = B(t)·w is taken before that year's return is applied. A path that reaches zero is marked ruined; the risk of ruin is the share of paths ruined by the end of the horizon.

🎮 How to use

Drag the amber sphere to set the annual contribution, the orange ring to set the withdrawal rate, or the vertical marker to set the retirement age — or use the matching sliders. 🎲 Reroll draws a fresh batch of random paths for the same plan.

💡 Did you know?

The classic "4% rule" comes from historical U.S. market studies suggesting a 4% initial withdrawal rate rarely exhausts a 30-year retirement portfolio — but it depends heavily on the sequence of returns you happen to get, which is exactly what this Monte Carlo cloud makes visible.

⚙ Under the hood

This simulation demonstrates the principles of financial planning for an aging population by allowing users to manage simulated assets and investments over time. It explores concepts like retirement savings, inflation, and investment risk.

Financial AgingModeling

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install