Online Compound Interest Calculator

Want to know how much your money can grow over time? Our compound interest calculator does the math in seconds — you just need to enter the initial amount, interest rate, and time period.

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What is compound interest?

Compound interest is known as "interest on interest".
Unlike simple interest, where the rate applies only to the initial amount, here each period adds interest to the total accumulated amount.

👉 Example: if you invest $1,000 at 10% per year, in the first year you'll have $1,100.
In the second year, the rate doesn't apply only to the initial $1,000, but to the $1,100 — resulting in $1,210.

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How to use the compound interest calculator

1. Enter the initial amount (e.g.: $5,000).
2. Enter the interest rate (e.g.: 8% per year).
3. Set the time period (in months or years).
4. Click Calculate.

✅ The result shows the final amount, accumulated interest, and period-by-period growth.

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Practical use examples

• Personal investments: simulate how much your money can grow in savings accounts, CDs, or government bonds.
• Financing and debt: understand the impact of installments and credit cards.
• Financial education: students can use the tool to learn how interest works.

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Frequently Asked Questions (FAQ)

What's the difference between simple and compound interest?

In simple interest, the rate applies only to the initial amount.
In compound interest, the rate applies to the accumulated amount each period.

Are compound interest always worth it?

Yes for investments, no for debt.
With debt, compound interest can grow quickly and become unpayable.

Which rate should I use? Monthly or annual?

It depends on how the financial institution presents the returns.
Our calculator accepts both.

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Tips and curiosities

• Einstein supposedly called compound interest "the most powerful force in the universe".
• The rule of 72 helps estimate how long it takes for a value to double: just divide 72 by the annual rate.
  • Example: at 12% per year, money doubles in ~6 years.
• A common mistake is confusing monthly with annual rates — always check before calculating.

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➡️ Test the compound interest calculator above now and discover how much your money can grow!