Project your retirement savings from current age, savings, monthly contributions, and expected return — see total savings at retirement, estimated monthly income, how long it will last, and a year-by-year growth chart.
Every dollar saved for retirement doesn't just sit still — it earns returns, and those returns themselves start earning further returns, a snowballing effect known as compounding that is, by a wide margin, the single most powerful force in long-term savings growth. A dollar saved at age 25 has decades longer to compound than the same dollar saved at age 45, which is why financial advisors so consistently emphasize starting early over waiting to save a larger amount later — time in the market, applied to compounding, tends to outweigh the size of any individual contribution.
This calculator's projection makes this concrete: the 'total investment growth' figure it reports (total savings at retirement minus your actual contributions) often ends up representing a majority of the final balance for anyone with a multi-decade time horizon, meaning the market's compounding did more work than your own contributions did. That's precisely the mechanism compounding is meant to produce, and it's why even modest, consistent monthly contributions started early can outperform much larger contributions started late.
The core formula behind this calculator's projections — future value of an annuity — combines two separate growth streams: your current lump-sum savings compounding on its own, and a stream of new monthly contributions each compounding from the moment they're added. The formula handles both simultaneously because that's exactly how a real retirement account behaves: existing money keeps growing while new money is continuously added and starts its own compounding clock.
This is the same underlying math used by 401(k) providers, robo-advisors, and financial planning software industry-wide, which is why this calculator's projections should closely match what you'd see from a brokerage's own retirement calculator given the same input assumptions — the formula itself is standardized; what varies between tools is mainly which default assumptions (return rate, inflation) are used.
The 4% safe withdrawal rate, used here to estimate monthly retirement income, originates from research examining historical US market returns across many overlapping 30-year retirement periods, finding that a 4% first-year withdrawal (adjusted for inflation thereafter) survived the vast majority of historical scenarios without running out. It has become the most widely cited retirement planning heuristic precisely because it's simple and grounded in real historical data rather than an arbitrary guess.
It does have real limitations worth understanding: it was derived from US market history and a specific stock/bond portfolio mix, it assumes a roughly 30-year retirement horizon (a shorter or notably longer retirement changes the math), and some more recent research argues a lower rate (closer to 3-3.5%) may be more conservative given current market valuations and longer life expectancies. This calculator uses 4% because it remains the standard reference point, but it's worth treating the resulting income figure as a reasonable planning estimate rather than a guaranteed number.
A retirement projection showing '$1.2 million at retirement' sounds impressive, but that figure means very little without context about what it will actually buy decades from now — inflation steadily erodes purchasing power, historically averaging around 2-3% annually in most developed economies, which compounds significantly over a 30-40 year working career. $1.2 million thirty years from now, discounted back to today's purchasing power at 3% inflation, is worth roughly $494,000 in today's terms — a meaningfully more sobering, and more useful, number for actual planning purposes.
This is why this calculator reports both the nominal total savings figure and the same total converted into today's dollars — the nominal figure is what your account statement will eventually show, but the inflation-adjusted figure is what actually matters for understanding your real future purchasing power and comparing it meaningfully against your current cost of living.
The year-by-year growth chart plots your projected account balance from your current age through your retirement age, and its shape reveals something important about how compounding actually works: the curve stays relatively flat and unremarkable in the early years, then visibly steepens in the later years as the accumulated balance itself becomes large enough for its own growth to meaningfully outpace new contributions. This visual pattern — often called the 'hockey stick' of compound growth — is completely normal and expected, and it's exactly why the final decade before retirement typically contributes a disproportionately large share of total growth compared to the first decade, even with identical contribution amounts throughout.
If your chart looks like it barely grows for years before finally accelerating, that's not a sign anything is wrong — it's simply how exponential growth behaves, and it's a strong argument for staying consistent with contributions through the early 'flat' years rather than getting discouraged and stopping before the compounding effect has had time to build meaningful momentum.
Retirement Calculator projects long-term savings growth. These related calculators cover other investment and savings math.