How a starting balance and steady contributions grow — and how much of the final number is your money vs. the market's.
Raise your contribution each year, e.g. alongside salary growth.
The S&P 500 has averaged ~10% nominal, ~7% after inflation, over long periods. Compounded monthly here.
This compound interest calculator shows how an initial balance plus steady contributions grow over time, and separates the final number into the money you put in versus the earnings the market added on top. It makes the power of compounding visible.
The calculator compounds your starting balance and regular contributions month by month at your expected return, optionally stepping up contributions each year. It then splits the final balance into the money you actually put in versus the earnings the market added on top, which makes the compounding effect visible. A real-value view discounts the result back to today's dollars.
Earnings are added to your balance and then earn returns themselves. Over long periods this snowball effect means most of your final balance can come from growth, not contributions.
More is always better, but consistency matters most. The calculator lets you test different monthly amounts to see their long-run impact.
A broadly diversified stock portfolio has historically returned around 7% per year after inflation, though future returns are never guaranteed.
Earnings get reinvested and then earn their own returns. Over decades this snowball means the majority of a long-term balance can come from growth rather than your contributions.
A broadly diversified stock portfolio has historically returned around 7% per year after inflation, but future returns are uncertain. Testing a lower rate gives a more conservative plan.
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