How to use this calculator
- Enter your age, when you plan to retire, and how long the money needs to last.
- Enter what you’ll spend each month in today’s dollars, and an inflation rate.
- Enter your savings so far, your monthly contribution, and how fast it grows.
- Pick a mix for each phase — the expected return defaults to that mix’s history.
- Check the strip of real market histories: red squares are the years your plan ran out.
History: US stocks (S&P 500), corporate bonds and 10-year Treasuries, and US inflation, 1928–2025(A. Damodaran, NYU Stern). The conservative mix averaged 6.8% a year; US prices rose 3% a year.
Frequently asked questions
How much do I need to retire?
Enough to cover every month of spending from your retirement date to the end of the plan, after other income and allowing for inflation. With the example here — $5,000 a month in today’s dollars, retiring at 65 and planning to 90 — that comes to about $2.37 million at 65.
What does “replayed through real markets” mean?
We rerun your retirement starting in each year since 1928, using what stocks, bonds and inflation actually did from that year on. In this example the money lasted in 63 of 98 histories; it ran short when retiring into 1934, 1935, 1936, 1937, 1938, 1939 and others.
Why can a plan that works on average still fail?
Sequence-of-returns risk: a market slump in the first years of retirement, while you are withdrawing, does far more damage than the same slump later on. That’s why the history check matters more than the average return.
Should I include Social Security?
Yes — enter your estimated monthly benefit as other income. You can get your estimate from your my Social Security account at ssa.gov. The calculator raises it with inflation.
Are taxes included?
No. Withdrawals from traditional 401(k)s and IRAs are generally taxable; Roth accounts and taxable accounts are treated differently. Plan for taxes on top of your spending figure.