Compound Interest Calculator
Enter your capital, monthly contribution and expected return. The calculator shows nominal growth, real inflation-adjusted value and estimated tax impact.
Nominal capital
447.156 €
Real capital (today's €)
213.178 €
Contributions
118.000 €
What is the difference between nominal and real return?
Nominal return is the gross yield on your investment. Real return subtracts inflation and shows how much purchasing power you actually gain in today's euros.
How does tax affect my gains?
Capital gains in Spain are taxed between 19% and 30% depending on the amount. This calculator applies the 2026 tax brackets to estimate your fiscal impact if you were to sell today.
Why does monthly contribution matter?
Regular contributions amplify compound interest. With €300/month for 30 years at 7%, accumulated capital exceeds €1,000,000 — of which over €700,000 are pure returns.
Where to get the initial capital?
Matched betting can be your starting point.
Many users spend their first months doing matched betting to build up seed capital before investing in index funds. No risk, bookmakers pay.
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