Compound Interest Calculator
Our compound interest calculator helps you visualize the powerful effect of compound interest on your investments in Germany.Updated on October 6, 2025
Compound interest is the process of earning returns not just on your initial investment, but on the accumulated interest as well.
Let’s calculate how your investments are accumulating over time
Compounding is the effect of interest on interest. Einstein called compounding the Eighth World Wonder because the effect is so powerful. The longer assets are invested at a high yield, the steeper the impact on the value.
Research shows that people who use the Rule of 72 make the best predictions. This rule says that with a return of 7,2 %, your money doubles every 10 years. So in:
10 years: 2x your money
20 years: 4x your money
30 years: 8x your money
40 years: 16x your money
Pensionfriend aims for a return of over 7,2 % after cost and tax, about 2% more than investing in a global ETF index, the MSCI. Make a free appointment here
Investfriend aims for even higher returns, but it does require a higher income to afford a new investment property. You can check the details here.