Compound Interest Calculator
Enter your starting amount, monthly contribution, interest rate and term to see your final balance and how much of it is interest.
Enter a deposit or a monthly contribution, the interest rate and the number of years.
Gross result, before taxes. Add an inflation rate to also see what it is worth in today’s money.
Year-by-year breakdown
Enter a deposit or a monthly contribution, the interest rate and the number of years.
Results are estimates. Solvemis accepts no responsibility for the results obtained or for how they are used. Always double-check the result and talk to a qualified professional before making decisions.
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How it works
How to use it
- Enter your starting amount and your monthly contribution. One of the two can be left empty.
- Enter the annual interest rate and the term in years.
- Choose how often interest is credited and whether you pay in at the start or the end of the month.
- If you want to know what the result is worth in today's money, enter the average inflation you expect. The European Central Bank aims for 2%.
- You will see the final balance, the total paid in and the interest earned, plus a chart of the growth. The table shows the progress year by year.
How it is calculated
The balance is simulated month by month. The annual rate is converted into the equivalent monthly rate according to how often interest is credited, (1 + r/n)^(n/12) − 1. Without a monthly contribution, the result matches the classic compound interest formula exactly. If you enter inflation, each balance is divided by (1 + inflation)^years to express it in today's money.
Final balance = P × (1 + r/n)^(n × years)
Sources
- Compound Interest Calculator — U.S. Securities and Exchange Commission (Investor.gov)
- Two per cent inflation target — European Central Bank
About this calculator
How compound interest works
Interest is added to the balance and earns interest itself in the next period. €10,000 at 5% over 10 years becomes €16,470 with monthly compounding; with €100 a month paid in, €31,998.
Inflation: what your money will be worth
If you enter the expected average inflation, the calculator also shows the value in today’s money: each balance is divided by (1 + inflation) to the power of the number of years. €16,470 in 10 years is worth about €13,511 today at 2% inflation. The European Central Bank aims for 2% inflation over the medium term.
Not included
The result is gross: without withholding tax on investment income (roerende voorheffing / précompte mobilier) or fees; inflation is only deducted if you enter it. For investments whose returns vary, such as equity funds, it is an illustration, not a forecast.
Frequently asked questions
What is the difference between simple and compound interest?
With simple interest, the interest is always calculated on the starting amount. With compound interest, it is added to the balance and earns interest itself. €10,000 at 5% over 10 years becomes €15,000 with simple interest and €16,289 with annual compounding.
Updated 1 October 2026
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