Retirement Savings Calculator

This calculator estimates what your retirement savings could grow to by combining a starting balance with monthly contributions, then compounding that combination at an assumed annual return. Each month, the running balance earns a share of the annual rate you enter, and any interest already earned starts earning its own interest going forward. On top of that, whatever you add every month keeps entering the account at today's dollar value while everything already inside keeps compounding. The result is a single number: your estimated balance on the day you reach your target retirement age — before you've spent a single dollar of it.

The single most expensive mistake in retirement planning is looking at that final number and thinking it reflects what your money can buy. It doesn't. Prices rise every year, so a dollar thirty years from now buys less than a dollar today. If your investments grow at 7% a year while prices rise at 3% a year, a balance that looks like $1,000,000 in thirty years is only worth roughly $412,000 in today's purchasing power — even though not a cent of it was spent or lost. That's why this calculator shows two numbers side by side: the nominal balance you'll actually see on a statement, and the real value once your assumed inflation rate is divided out. Planning around the nominal number alone is how people end up retiring with what looks like plenty and turns out to be considerably less.

Time in the market does more heavy lifting than the rate of return, because compounding is exponential rather than linear. Consider two people who both plan to retire with the same monthly contribution: one starts at 25, the other at 35. Even though the second person contributes for ten fewer years, most people assume the gap is modest — in reality, the first decade of contributions the early starter makes has three or four extra decades to compound, so they can end up with a meaningfully larger balance despite contributing far less money out of pocket over their lifetime. A decade is often the single most valuable input into this calculator, more valuable than a percentage point or two of return.

Because the monthly contribution keeps entering the calculation at every remaining compounding period, even a modest increase can matter enormously over a multi-decade horizon. Raising a monthly contribution by a relatively small amount, sustained for thirty years at a moderate return, can add tens of thousands of dollars to the final balance — often far more than the extra dollars actually contributed, because each additional dollar also compounds for however many years remain. If you're years away from retirement, small increases to the monthly contribution field are worth experimenting with; they tend to move the final number more than most people expect.

This calculator has real limits worth understanding before you rely on it. It assumes the same annual return every single year, but real markets move up and down — a portfolio might gain 20% one year and lose 15% the next, and a string of bad years right before retirement (sometimes called sequence-of-returns risk) can do far more damage than the same losses spread evenly across decades, even if the long-run average is identical. The tool also ignores taxes, account fees, and expense ratios, all of which reduce what you actually keep. Finally, it stops at the day you retire — it says nothing about how long that balance needs to last, how much you'll spend each year afterward, or how withdrawals should be managed once you stop contributing.

Treat every result here as an educational simulation, not financial advice, a projection of what will happen, or a promise of any specific return. The expected annual return you enter is your own assumption about the future — this calculator doesn't recommend a rate, a product, or an investment strategy, and no real portfolio grows at a perfectly steady rate year after year. Retirement systems like 401(k)s and IRAs in the U.S. have their own rules around contributions and taxes that this general-purpose calculator doesn't model; check the specifics of whatever accounts you actually use.