What this tool does
This Compound Interest Calculator shows how your money grows when interest is added back and earns more interest over time, and it goes beyond a simple lump sum by letting you add regular monthly or yearly contributions. It is handy for savers comparing accounts, investors estimating long term returns, students learning the formula, and anyone building a savings plan. Instead of guessing, you get a final balance split three ways into your starting amount, your total contributions, and the interest earned, shown across three summary cards, a year-by-year table, and a stacked growth chart. It is currency-agnostic, so it works with any currency.
How to use it
- Enter your Starting amount, the Annual interest rate (%) (for example 5 for five percent), the number of Years, and how often interest is added in the Compound frequency menu (annually, semiannually, quarterly, monthly, or daily).
- Add a Regular contribution amount and choose a Contribution frequency of monthly, yearly, or none, then set whether each deposit is added at the start or end of the period.
- Results update instantly as you type, with no Calculate button to press.
- Read your final balance and the split showing how much came from your starting amount, your total contributions, and the interest earned.
- Open the collapsible year-by-year table to see contributions to date, interest to date, and the balance for each year, and read the stacked bar chart to watch starting amount, contributions, and interest grow side by side.
A quick worked example
Enter 1000 as your Starting amount, set the Annual interest rate (%) to 5, enter 10 in Years, and pick monthly in Compound frequency. With no contribution, the balance grows to about 1647, meaning roughly 647 in interest on top of your original 1000. Now add a regular monthly contribution of 100 and watch the results update live: the final balance jumps, the summary cards show a large slice coming from your total contributions, and the growth chart and year-by-year table fill in so you can see exactly when each part of the balance builds up. Try switching the compound frequency to annually or daily to see how the result shifts slightly, a clear way to understand why compounding matters.
Everything runs right in your browser, so your numbers stay private and never leave your device. It is completely free and needs no sign-up.
Frequently asked questions
- How is compound interest different from simple interest?
- Simple interest is earned only on your original starting amount, while compound interest is earned on the starting amount plus any interest already added. Over time, compounding grows your balance much faster.
- Does compound frequency really matter?
- Yes, but the effect is smaller than many people expect. More frequent compounding (monthly or daily) earns slightly more than annual compounding at the same rate, with the gap widening over longer periods. You can switch between annually, semiannually, quarterly, monthly, and daily to compare.
- Can I add regular monthly or yearly contributions?
- Yes. Enter a contribution amount and choose whether it repeats monthly, yearly, or not at all. You can also set whether each deposit lands at the start or end of the period. The calculator adds these deposits over time and shows how much of your final balance came from them.
- What is the difference between contributions and interest in my total?
- Your final balance is split three ways: your starting amount, your total contributions (every deposit you made), and the interest earned (the growth on top of everything you put in). The summary cards and the growth chart make this split easy to see at a glance.
- What rate should I enter?
- Enter the annual interest rate as a percent, for example 5 for five percent. Use the nominal yearly rate quoted by your bank or account, and the calculator applies it across the compound frequency you choose.
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Last updated: June 17, 2026