Compound interest calculator
See what regular contributions and compounding do to a portfolio over years and decades. Adjust the compounding frequency to compare annual, monthly, and daily compounding side by side.
Amount at day zero (EUR).
Nominal annual rate, per year.
Total horizon in whole years.
Added at the end of each compounding period.
Periods per year used to compound interest.
- All amounts in EUR (€); rate is a nominal annual percentage.
- Interest compounds at the selected frequency (n): effective per-period rate = rate ÷ n.
- Monthly contribution is annualised then split evenly across the n periods per year (deposited at period end).
- Gross of fees, taxes and inflation.
- Illustrative only; assumes a constant return with no volatility.
| Year | Balance (€) | Contributed (€) | Interest (€) |
|---|---|---|---|
| 1 | €13,201 | €12,400 | €801 |
| 2 | €16,634 | €14,800 | €1,834 |
| 3 | €20,315 | €17,200 | €3,115 |
| 4 | €24,262 | €19,600 | €4,662 |
| 5 | €28,495 | €22,000 | €6,495 |
| 6 | €33,033 | €24,400 | €8,633 |
| 7 | €37,900 | €26,800 | €11,100 |
| 8 | €43,118 | €29,200 | €13,918 |
| 9 | €48,714 | €31,600 | €17,114 |
| 10 | €54,714 | €34,000 | €20,714 |
| 11 | €61,147 | €36,400 | €24,747 |
| 12 | €68,046 | €38,800 | €29,246 |
| 13 | €75,444 | €41,200 | €34,244 |
| 14 | €83,376 | €43,600 | €39,776 |
| 15 | €91,882 | €46,000 | €45,882 |
| 16 | €101,003 | €48,400 | €52,603 |
| 17 | €110,783 | €50,800 | €59,983 |
| 18 | €121,270 | €53,200 | €68,070 |
| 19 | €132,515 | €55,600 | €76,915 |
| 20 | €144,573 | €58,000 | €86,573 |
How this calculator works
Each period the balance grows by rate / periods_per_year. Monthly contributions are distributed across those periods so the compounding-frequency choice compares fairly.
The year-by-year table shows the ending balance, cumulative contributions, and cumulative interest — the third column is where compounding shows up.
Figures are illustrative only. Not investment, tax, or legal advice. Capital at risk.