Why the contribution habit matters more than the rate
Over short time horizons, what you contribute dominates the total. Over long ones, growth on growth starts to take over — which is why starting early tends to matter more than chasing a slightly higher return. This calculator separates the two so you can see exactly how much of your final balance is money you actually put in.
A worked example
Starting with $10,000 and adding $200 a month at a 7% annual return, compounded monthly, grows to roughly $144,600 after 20 years. Of that, only about $58,000 was actually contributed — the rest, almost $86,600, is pure growth. Extend the timeline to 30 years in the calculator above and the balance climbs past $325,000, with growth making up roughly three-quarters of it.
Frequently asked questions
What does compounding frequency actually change?
It controls how often earned interest gets added to your balance so it starts earning its own interest. Daily compounding grows a balance very slightly faster than monthly, which in turn is slightly faster than annual — the difference is usually small unless rates are high or the time horizon is long.
What return rate should I use?
For a savings account, use the actual advertised APY. For investments, there's no guaranteed number — long-run stock market averages are often cited in the 6–10% range before inflation, but any individual year can be sharply higher or lower. Try a few different rates to see a realistic range of outcomes.
Why does the growth line curve upward instead of staying straight?
That curve is compounding in action — early growth is mostly driven by your contributions, but as the balance grows, the interest earned on previous interest becomes a bigger share of each year's growth. This effect accelerates the longer the money stays invested.
Does this account for taxes or inflation?
No — this shows nominal growth before taxes on gains (if any apply in a taxable account) and before inflation erodes purchasing power. Both can meaningfully change the real-world value of the future amount shown.
This calculator provides estimates for general informational purposes only and is not financial or investment advice. Actual returns are not guaranteed and can be negative in any given year — consult a licensed financial advisor for personalized guidance.