See the power of compounding: a starting balance plus monthly contributions growing at a chosen annual return.
How the Compound Interest Calculator works
Compound interest earns returns on both your principal and previously earned interest. The calculator grows a starting balance plus optional monthly contributions at your chosen rate and compounding frequency.
Example calculation
$10,000 plus $300 a month at 7% for 25 years grows to roughly $300,000 — only about $100,000 of which is money you contributed.
Tips for using the Compound Interest Calculator
- Start early — time matters more than amount.
- Reinvest all earnings to keep compounding.
- More frequent compounding gives a slightly higher result.
Compound Interest Calculator — frequently asked questions
- What return should I use?
- A diversified stock portfolio has historically averaged ~7% per year after inflation long term, but returns vary.
- Does frequency matter?
- More frequent compounding slightly increases growth; monthly is realistic for most accounts.
- What rate should I assume?
- Diversified equities have historically averaged ~7% after inflation long term, but returns vary year to year.
- Daily vs monthly compounding?
- Daily compounds marginally faster; the difference is small versus contribution size and time.
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