What does this simulation show?
A normal calculator assumes the same return every year. Real markets go up and down. Monte Carlo accounts for randomness: we run your plan hundreds of times with different swings and look at all outcomes.
Why it beats a single number
Two plans with the same average return but different risk (volatility) give very different results. The higher the volatility, the wider the spread and the lower the chance of confidently reaching your goal. Managing risk is what separates professionals — it's essentially what BlackRock is built on.
Simplified model (normal distribution). Educational purposes only, not financial advice.