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Compound Interest Calculator

Initial capital

The amount you invest at the beginning.

Monthly contribution

Optional amount added every month.

Average annual return

Expected average yearly return. It is not guaranteed.

Years

Investment duration from 1 to 100 years.

Compounding frequency

Monthly compounding applies interest every month. Yearly compounding applies it once per year.

Compound interest result

Final balance

$96,112.46

Interest earned

$43,112.46

Total invested

$53,000.00

Growth multiple

1.81x

Growth curve

Estimated balance at the end of each year.

20 years

Year	Contributions	Interest	End balance
1	$2,400.00	$321.81	$7,721.81
2	$2,400.00	$461.07	$10,582.88
3	$2,400.00	$607.44	$13,590.32
4	$2,400.00	$761.31	$16,751.63
5	$2,400.00	$923.05	$20,074.68
6	$2,400.00	$1,093.06	$23,567.74
7	$2,400.00	$1,271.77	$27,239.52
8	$2,400.00	$1,459.63	$31,099.15
9	$2,400.00	$1,657.09	$35,156.24
10	$2,400.00	$1,864.66	$39,420.91
11	$2,400.00	$2,082.85	$43,903.76
12	$2,400.00	$2,312.20	$48,615.96
13	$2,400.00	$2,553.29	$53,569.25
14	$2,400.00	$2,806.71	$58,775.96
15	$2,400.00	$3,073.09	$64,249.05
16	$2,400.00	$3,353.11	$70,002.16
17	$2,400.00	$3,647.45	$76,049.60
18	$2,400.00	$3,956.85	$82,406.45
19	$2,400.00	$4,282.07	$89,088.52
20	$2,400.00	$4,623.94	$96,112.46

This calculator is for educational purposes only. Returns are estimates based on the values entered and do not represent financial advice or guaranteed performance.

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How it works

Calculate compound interest on an investment, add optional monthly contributions and visualize how your capital may grow year by year.

Practical examples

Monthly investing plan

Start with $5,000, add $200 per month and estimate the result after 20 years at an average annual return of 5%.

Try this example →

One-time investment

Estimate how $10,000 could grow over 15 years with a 4% average annual return and no extra contributions.

Try this example →

Long-term savings scenario

Compare the effect of time by simulating a 30-year plan with regular monthly contributions.

Try this example →

FAQ

What is compound interest?

Compound interest means that interest is calculated not only on the initial capital, but also on the interest accumulated over time. This is why long time horizons can have a strong impact on the final result.

Can I include monthly contributions?

Yes. Enter a monthly contribution to estimate how regular investing may change the final balance compared with a one-time investment.

Is the annual return guaranteed?

No. The annual return is only an assumption used for the calculation. Real investments can go up or down, and past performance does not guarantee future results.

Does this calculator send my data anywhere?

No. The calculation runs in your browser. Values may be saved locally on your device to restore the last scenario, but they are not sent to an external server.