RechnerpediaHow the interest calculator works
Lump sum: K_n = K_0 × (1 + p/m)^(m × n) Savings plan: interest accrues monthly and is credited at the end of each interest period Tax: (interest of the year − allowance) × 26.375% Real value: K_n ÷ (1 + inflation)^n
Once interest is credited, it earns interest too: that is compound interest. The more often interest is credited, the higher the effective annual rate: 3% credited monthly equals 3.042% effective. For savings paid in during a year with yearly crediting we use the usual German savings bank method: each deposit earns interest pro rata for the remaining months.
Interest and tax in Germany
Interest is capital income. Above the saver’s allowance (Sparer-Pauschbetrag) of €1,000 (€2,000 for married couples), German banks withhold 25% flat tax (Abgeltungsteuer) plus the 5.5% solidarity surcharge, 26.375% in total. With church tax it is 27.82% (8%) or 28% (9%). For the allowance to apply you need to give your bank an exemption order (Freistellungsauftrag). Accounts at foreign banks do not withhold German tax; you then declare the interest in your tax return.
In the example above, a €10,000 starting amount plus €100 a month at 3% grows to €27,419.37 in ten years, of which €0.00 goes on tax. In today’s purchasing power at 2% inflation that is €22,493.43. Without the monthly saving and without tax, €10,000 becomes €13,439.16.
| Rate | Final balance | Total interest | Doubles after |
|---|---|---|---|
| 1% | €11,046.22 | €1,046.22 | 69.7 years |
| 2% | €12,189.95 | €2,189.95 | 35 years |
| 3% | €13,439.16 | €3,439.16 | 23.4 years |
| 4% | €14,802.44 | €4,802.44 | 17.7 years |
| 5% | €16,288.94 | €6,288.94 | 14.2 years |
| 7% | €19,671.52 | €9,671.52 | 10.2 years |
Sources
- § 32d EStG, flat tax on capital income (German)
- § 20 EStG, saver’s allowance (German)
- Destatis: inflation rate October 2026 (German)
Frequently asked questions
How do I calculate compound interest?
Multiply the capital by (1 + interest rate) for each year. At 3% over 10 years: €10,000 × 1.03¹⁰ = €13,439.16. The calculator also handles interest credited during the year and monthly savings.
How much tax do I pay on interest in Germany?
Above the saver’s allowance, 26.375% (flat tax and solidarity surcharge), with church tax just under 28%. If your overall personal tax rate is lower, you can get money back through the favourable tax assessment in your tax return.
What is the difference between nominal and effective interest?
The nominal rate is the agreed annual rate. The effective rate takes into account how often interest is credited. With monthly crediting it is slightly higher than the nominal rate.
What is my money worth after inflation?
Divide the final balance by (1 + inflation rate) to the power of the number of years. If the interest rate after tax is below inflation, you lose purchasing power despite the interest.
When does my money double?
Rule of thumb: 72 divided by the interest rate. At 3% after about 24 years, at 6% after about 12 years. The calculator shows the exact value.