Will your nest egg last? Enter your savings, how much you plan to withdraw each year, and your assumptions for returns and inflation. This calculator shows how many years your money survives, your monthly income, and how your plan compares to the famous 4% rule.
How long your savings last
Accumulating a nest egg is only half the battle. The harder, scarier question comes at retirement: how much can you actually pull out each year without running dry before you run out of life? Withdraw too little and you needlessly pinch pennies in the years you should be enjoying. Withdraw too much and you risk the nightmare scenario of outliving your money. This calculator models the tug-of-war between three forces — your withdrawals draining the account, investment returns refilling it, and inflation quietly forcing you to take out more each year just to maintain the same lifestyle.
That inflation piece is the part casual estimates miss. A $45,000 withdrawal feels fixed, but to buy the same groceries and pay the same bills in twenty years you might need $80,000 or more. A realistic plan increases your withdrawal every year to keep pace with rising prices, which is exactly what this tool does — it grows your annual withdrawal by your inflation assumption while compounding the remaining balance at your expected return. When the two forces cancel out, your money can last decades; when withdrawals outrun returns, you'll see the timeline shrink fast. Watching how sensitive the result is to small changes in return or withdrawal is the single best argument for building in a margin of safety.
This is also where the famous 4% rule comes from. Research suggested that withdrawing about 4% of your starting balance in year one, then adjusting for inflation annually, gave a high probability of lasting at least 30 years through historical market conditions. The calculator shows you what 4% of your nest egg would be so you can sanity-check your own plan against that benchmark. Remember it's a guideline, not a guarantee — real markets don't deliver smooth average returns, and a run of bad years early in retirement (what advisors call sequence-of-returns risk) can do outsized damage. Treat the output as a planning compass and stay flexible enough to trim withdrawals when markets sag.
Your withdrawals must rise yearly to keep their buying power. A "fixed" income quietly shrinks over decades.
Drawing ~4% of your starting balance, adjusted for inflation, has historically lasted about 30 years.
Poor returns early in retirement hurt most. Staying flexible with withdrawals protects against bad timing.
Withdrawal planning asks how long a portfolio lasts at a given spending rate, or what rate a portfolio can sustain for a given period. It is the annuity formula run in reverse, but with a complication that annuities do not have: the return is variable, and withdrawals taken during a downturn permanently remove shares that cannot participate in the recovery. This is why the safe withdrawal rate — around 4% for a 30-year horizon — sits so far below the 7% or so a balanced portfolio is expected to earn. The gap is the price of surviving a bad first decade.
Sustainable withdrawal = Portfolio × safe withdrawal rateYears lasting = −log(1 − (r × P) ÷ W) ÷ log(1 + r)Inflation-adjusted: increase the withdrawal by CPI each yearPerpetual (never depleting): W = P × real returnwhere:
Assumptions: Based on historical US data. Assumes annual rebalancing and that withdrawals rise with inflation. Flexible spending — cutting withdrawals in bad years — materially improves survival odds and is the most effective real-world adjustment.
Convert an accumulated balance into sustainable income, and test a higher rate.
Result$58,152 a year ($4,846/month) at the 4% rule
The difference between 3.5% and 5% is $21,807 a year of income against a meaningful risk of depletion — which is the central trade-off of retirement. Retiring into a market peak argues for the lower end; retiring after a crash, when valuations are already reset, historically supported the higher.