How to use it
- Enter your starting amount.
- Set the annual interest rate.
- Specify years and monthly contribution.
- Click Calculate to see results.
Our free Compound Interest Calculator shows exactly how much your money will be worth after a chosen period, accounting for both the initial lump sum and any regular monthly contributions. Simply plug in the starting balance, the annual percentage yield, the number of years you plan to invest, and how much you’ll add each month. The tool instantly returns three key figures: Future Balance – the total amount you’ll have, Total Put In – the sum of your original deposit plus all contributions, and Interest Earned – the growth generated by compounding. Understanding these numbers helps you set realistic savings goals, compare investment options, and stay motivated as you watch your wealth accumulate over time. You can also adjust the inputs to model different scenarios and instantly see how changes affect your final outcome.
Pro tips
- Round interest rates to two decimals for realistic results.
- Enter contributions as the amount you actually deposit each month, not annually.
- Use whole years; partial years can be approximated by adjusting the monthly contribution.
- Double‑check that your starting amount and contributions are in the same currency.
Real-life examples
- Planning retirement savings and want to know the balance at age 65.
- Saving for a down‑payment on a house and need to see if a 5‑year plan works.
- Comparing two investment accounts with different interest rates to choose the better option.
Case study
Maria started with $5,000, added $300 each month, and expected a 4% annual return over 10 years. After entering her numbers, the calculator showed a future balance of $57,000, with $36,000 contributed and $21,000 earned as interest, confirming her goal was achievable.