Building the corpus is only half the problem — spending it without running out is the other half. This simulates your withdrawals year by year through retirement. For the accumulation side (how much to save monthly to get there), see the FIRE calculator.
Simulated year by year: each year's withdrawal grows with your assumed inflation, the remaining corpus grows at your assumed post-retirement return, then the year's withdrawal is taken out. "Max sustainable withdrawal" is solved to leave the corpus at exactly zero at your planning age — treat it as a ceiling, not a target, since real returns are never a smooth constant line. This is a planning estimate, not investment advice.
The percentage of your retirement corpus you can withdraw each year with a low risk of running out of money before you do. 4% a year is the commonly cited starting point, though it assumes a specific mix of returns and inflation that may not match yours — that's what the simulator above checks directly.
A common shortcut is 25 times your annual expenses (the "25x rule," based on a 4% withdrawal rate). It's a reasonable starting estimate, but your real number depends on your expected post-retirement returns, inflation, and how long you'll need the money — run the simulator above with your own figures.
A guideline suggesting a retirement corpus can sustain a 4% annual withdrawal, adjusted for inflation, for roughly 30 years without running out. It comes from historical market data and is a reference point, not a guarantee.
Significantly — if your withdrawals grow with inflation each year but your corpus doesn't grow faster than that, it depletes much sooner than a flat-withdrawal estimate would suggest. The simulator above models that year by year.
Your M∞ account tracks your actual portfolio and net worth automatically, so numbers like this stay current — free.
More planning tools Create free account