WorldCalcs

Compound Interest Calculator

See how your savings grow with compound interest, at any frequency.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: June 2026

Final balance

16 470.09

Total interest earned

6 470.09

Works for any currency — results are in whatever currency you enter.

This is a general estimate, not financial advice. Real returns vary and are not guaranteed. See our Disclaimer.

What is compound interest?

Compound interest is interest earned on both your original money and the interest already added, so your balance grows faster over time than with simple interest. It is often called "interest on interest", and it is the engine behind long-term savings and investment growth. The more often interest is compounded (yearly, monthly, daily) and the longer it runs, the bigger the effect. This calculator shows the final balance and interest earned, with a year-by-year breakdown.

How it's calculated

The formula is A = P x (1 + r/n)^(n x t), where P is the starting principal, r is the annual rate as a decimal, n is how many times a year interest compounds, and t is the number of years. The interest earned is simply A minus P. Compounding more frequently raises the result slightly, and time is the biggest lever.

Example

10,000 invested at 5% for 10 years, compounded monthly, grows to 16,470.09, which is 6,470.09 in interest. Compounded once a year instead, it reaches 16,288.95, a little less because interest is added less often.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Enter your starting principal, annual interest rate, how often interest compounds, and the number of years. Results update instantly as you type.

The final balance is what your account is worth at the end. Interest earned is the part of that balance that came from interest, not your original deposit.

Frequently asked questions

What is compound interest?+

Interest calculated on the principal plus previously earned interest, so growth accelerates over time.

What is the difference between compound and simple interest?+

Simple interest is only on the principal; compound adds interest on the interest. See our Simple Interest Calculator.

How does compounding frequency matter?+

More frequent compounding (monthly vs yearly) gives a slightly higher final balance.

What is the rule of 72?+

A quick estimate: divide 72 by the annual rate to get the years to double; at 6%, about 12 years.

How is compound interest calculated?+

With A = P(1 + r/n)^(nt); interest earned is A minus the principal.

Why is time so important?+

Because each year's interest itself earns interest, the longest time horizons produce the largest growth.

Does this include regular deposits?+

No; for ongoing monthly contributions, see our Savings Calculator.

Is the return guaranteed?+

No; real rates vary, and this is an estimate, not financial advice.

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