How does compounding frequency affect the result?

More frequent compounding grows money slightly faster because interest is added to the balance sooner and starts earning its own interest. The difference between monthly and annual compounding at typical savings rates is small but real.

Does this account for inflation or taxes?

No. The projection is nominal, it ignores inflation, taxes, and fees, all of which reduce real returns. Treat it as an illustration of the math, not a guarantee of future performance.

Is my financial data stored anywhere?

No. The calculation runs entirely in your browser. Nothing you enter is sent, stored, or shared.

Compound Interest Calculator

See how your savings grow over time with compound interest and monthly contributions.

Currency

Initial deposit ($)

One-time amount you start with.

Monthly contribution ($)

Added at the end of each month.

Annual interest rate (%)

Nominal rate before inflation and taxes.

Years to grow (1–50)

Compounding frequency

Projected balance after 20 years

$145,180

Total contributions

$58,000

Interest earned

$87,180

Growth year by year

Year 1Year 11Year 20

Hover over a bar to see the projected balance for that year.

Simplified model: monthly contributions are added at the end of each month, then interest compounds at your selected frequency. Ignores inflation, taxes, fees, and rate changes. Calculated in your browser, nothing is sent anywhere.

About this tool

Compound interest is often called the most powerful force in personal finance, and this calculator lets you watch it work. Enter an initial deposit, a monthly contribution, an annual rate, and a time horizon, and you will see your projected balance, plus exactly how much of it came from your contributions versus interest doing the heavy lifting.

The year-by-year growth chart makes the effect visual: early years are dominated by your own contributions, while later years show interest taking over as the balance compounds. Try changing the time horizon from 10 to 30 years to see why financial advisors stress starting early, the extra decades of compounding usually dwarf any realistic increase in monthly contributions.

How to use the compound interest calculator

1Enter your initial deposit and how much you will add each month.
2Set the annual interest rate and how many years the money will grow.
3Choose a compounding frequency (monthly, quarterly, semi-annual, or annual).
4View your projected balance, the contributions-vs-interest split, and the growth chart.
5Adjust the inputs to see how starting earlier or contributing more changes the outcome.

Good to know

The model is deliberately transparent: contributions are added at the end of each month and interest compounds at the frequency you choose. It does not predict market returns, and it ignores inflation, taxes, and fees, so use it to build intuition and compare scenarios rather than as a promise of what you will actually earn. All math happens locally in your browser, your numbers never leave your device.

Frequently asked questions

Compound interest means you earn interest not only on your original deposit but also on the interest already earned. Over time the growth accelerates, which is why starting early matters so much, time is the most powerful input.

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