Compound Interest Calculator
See how your savings grow over time with compound interest — adjust your contributions, rate and timeframe and watch the curve respond.
2026 rates · Last reviewed: 2026
Growth over time
The most powerful idea in saving
Compound interest means your interest earns interest. Each period's gain is added to your balance, so the next period you earn a return on a bigger number. Over years, the growth curve bends sharply upward — which is why starting early matters more than starting big.
What the chart shows
The gold dashed line is the money you actually put in. The green line is your balance. The widening gap between them is compounding at work — interest stacking on interest. Early on the two lines hug each other; later, the green line pulls away dramatically.
What moves the result most
- Time — the longest lever, and the one you can't buy back. An extra decade often matters more than an extra few percent.
- Rate of return — small differences compound into big gaps. Try 6% vs 8% above.
- Regular contributions — steady monthly deposits supercharge the curve.
- Compounding frequency — monthly slightly beats annual.
For the intuition behind all this, read what is compound interest.
This calculator provides estimates for general information only and is not financial or tax advice. See our disclaimer.