Compound interest calculator

Compounding is the quiet engine behind almost every long-term money outcome, and it’s easier to feel with your own numbers than to read about. Enter a starting balance, a monthly contribution, a rate, and a timeline — the calculator shows the ending balance and how much of it is growth rather than deposits.

Illustrative only — real returns vary year to year.

What the table is really showing

Look at the gap between “contributed” and “balance” as the years pass: early on, deposits do all the work; later, growth-on-growth takes over. That handoff is the whole argument for starting early — time in the market is the input that can’t be substituted later.

What compound interest is and why it matters explains the concept from zero, and starting to invest with little money covers the practical first steps. For the parking-money side, see high-yield savings accounts, and for whether growth math should ever wait, pay off debt or save first.

Sources & further reading

This tool is general education, not personalized financial advice. Steady-rate compounding is an illustration — real investments fluctuate and can lose value. See our disclaimer.