Retirement Calculator

It runs month by month. Each month the balance earns the monthly rate that compounds to your yearly return, (1 + annual return)^(1/12) − 1, and then your contribution and any employer match are added. Your contribution rises by the annual raise percentage every 12 months. With no raise, no match and a 0% return, the nest egg is simply your savings plus 12 × the monthly amount × the years to retirement.

The income you want, minus other income, is raised by inflation every year and withdrawn at the start of each year until your planning age, while the rest earns the post-retirement return. The nest egg needed for that is W × [1 − ((1 + g) ÷ (1 + r))^n] ÷ (r − g) × (1 + r), where W is the first year’s withdrawal, g inflation, r the return and n the years in retirement. The sustainable income is your projected nest egg divided by the same factor, shown in today’s money.

It comes from William Bengen’s 1994 study in the Journal of Financial Planning: using US market history from 1926, withdrawing 4% of a 50/50 stock and bond portfolio in the first year and raising that amount with inflation never ran out in under 33 years. The 1998 “Trinity study” by Cooley, Hubbard and Walz found similar results with 1926–1995 data. Both used past US returns, ignored fees and taxes, and assumed rigid spending over about 30 years, so the calculator shows 4% only as a reference point, not a safe guarantee.

No. The calculator does not model taxes of any kind. It treats contributions, growth and withdrawals as if no tax applied, which is not how traditional 401(k) and IRA withdrawals (taxed as income) or taxable accounts work. If most of your savings are pre-tax, the income you can spend will be lower than shown, so consider entering your desired income before tax.

For 2026 the IRS set the 401(k), 403(b) and governmental 457 employee limit at $24,500, with an $8,000 catch-up from age 50 and $11,250 for ages 60 to 63; the IRA limit is $7,500, with a $1,100 catch-up from age 50 (IRS news release IR-2025-111, 13 November 2025, checked 25 September 2026). The calculator does not enforce these limits.

There is no right number, and returns are never steady year to year. Use a long-run figure you consider realistic after fund fees, often lower after retirement if you plan to hold more bonds and cash, and test a lower one too. For inflation, compare with the long-run average of the Consumer Price Index. A small change in either compounds over decades, so try a pessimistic case before relying on any result.