Compound Interest Calculator
See how savings grow with compound interest and regular contributions.
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Enter an amount, rate, and number of years.
This compound interest calculator shows how an initial amount grows over time as interest is added and then earns interest of its own. You can set the annual rate, the number of years, how often interest compounds, and an optional monthly contribution to model regular saving.
The result splits the final balance into the money you put in and the interest earned, so you can see the effect of compounding at a glance. Every figure is calculated in your browser, and nothing you enter is uploaded or stored.
How to use
- Enter the initial amount you are starting with.
- Set the annual interest rate as a percentage and the number of years.
- Choose how often interest compounds, and optionally add a monthly contribution.
- Read the final balance, along with your total contributions and the interest earned.
FAQ
- How does compound interest work?
- Interest is added to the balance at each compounding period, and future interest is then calculated on the larger balance. Over time this makes savings grow faster than simple interest, which is paid only on the original amount.
- Does compounding frequency matter?
- Yes. More frequent compounding — monthly or daily rather than annually — produces a slightly higher final balance for the same annual rate, because interest starts earning interest sooner.
- How are monthly contributions treated?
- Each monthly contribution is added and compounds from the month it is paid in, so amounts added earlier earn more interest than those added later in the term.
- What currency does it use?
- The calculator is currency-neutral and works with plain numbers, so you can use it for any currency by reading the results in the same units you entered.
- Is my data sent anywhere?
- No. The calculation runs entirely in your browser with JavaScript. The values you enter are never transmitted, saved, or shared.