Why compound interest is so powerful
Compound interest means you earn returns not just on your deposits, but on the returns those deposits already earned. Over decades, this snowball effect can make the interest portion larger than everything you contributed.
The formula
FV = P(1+r)n + PMT · ((1+r)n − 1) / r
- P — starting amount
- PMT — monthly deposit
- r — monthly return
- n — number of months
How to grow it faster
- Start early — time matters more than amount.
- Automate deposits so you never skip a month.
- Reinvest everything; don't withdraw the gains.
Frequently asked questions
Is this guaranteed?
No. Investment returns vary year to year. This shows a steady-rate estimate to illustrate compounding.
What return should I assume?
A diversified stock index has historically averaged ~7% after inflation, but past results don't guarantee the future.
Does it include taxes?
No — it shows gross growth. Taxes depend on your account type and country.
Methodology and assumptions
- Instant browser math: results update from the inputs on this page and are not sent to an account.
- Next-step design: the score and action prompt are meant to help you compare scenarios and take one small practical step.