📈 Compound Interest Calculator
See how your money grows over time with compound interest. Add regular contributions, adjust for inflation and tax, and watch the results update instantly.
Enter your values
- Total invested€10,000.00
- Interest earned€90,626.57
- Tax paid€0.00
- Value after inflation€100,626.57
- Total growth906.27%
What this means
- Initial investment: €10,000.00
- Growth generated: €90,626.57
- Your investment increased by 906.27%
Visual results
Detailed breakdown
| Year | Contributions | Interest | Balance |
|---|---|---|---|
| 1 | €10,000.00 | €800.00 | €10,800.00 |
| 2 | €10,000.00 | €1,664.00 | €11,664.00 |
| 3 | €10,000.00 | €2,597.12 | €12,597.12 |
| 4 | €10,000.00 | €3,604.89 | €13,604.89 |
| 5 | €10,000.00 | €4,693.28 | €14,693.28 |
| 6 | €10,000.00 | €5,868.74 | €15,868.74 |
| 7 | €10,000.00 | €7,138.24 | €17,138.24 |
| 8 | €10,000.00 | €8,509.30 | €18,509.30 |
| 9 | €10,000.00 | €9,990.05 | €19,990.05 |
| 10 | €10,000.00 | €11,589.25 | €21,589.25 |
About this calculator
What this calculator does
This compound interest calculator shows how an investment or savings balance grows over time when the interest you earn is reinvested and itself starts earning interest. You can include an initial lump sum, regular monthly or annual contributions, different compounding frequencies, and optional adjustments for inflation and tax — and the results, chart, and year-by-year table update instantly as you type.
The formula
Compound interest with regular contributions is calculated period by period. For a lump sum, the core formula is:
A = P × (1 + r/n)^(n × t)
where:
- A — the final amount
- P — the principal (initial investment)
- r — the annual interest rate (as a decimal)
- n — the number of compounding periods per year
- t — the number of years
When you add regular contributions, each contribution is added at the end of its period and then compounds for the remaining time, which this calculator models directly.
How to interpret your results
- Final value is what your balance is worth at the end of the term (after any tax on gains).
- Total invested is the money you actually put in — your principal plus every contribution.
- Interest earned is the difference between the two: growth created purely by compounding.
- Value after inflation restates the final balance in today’s purchasing power, so you can judge your real return.
A small change in the interest rate or the time horizon has an outsized effect, because compounding is exponential. Time is the most powerful input — starting a few years earlier often beats contributing more later.
Common use cases
- Projecting long-term savings or an investment portfolio
- Comparing the impact of different rates of return (use the comparison feature)
- Understanding the cost of waiting to start investing
- Setting a retirement or education-fund target and working back to a monthly contribution
Related guides
Frequently asked questions
What is compound interest?
Compound interest is the interest you earn on both your original money and on the interest it has already earned. Over time this creates exponential, snowball-like growth — which is why starting early matters so much.
How does compounding frequency affect my returns?
The more often interest is compounded — daily versus annually, for example — the faster your balance grows, because interest starts earning its own interest sooner. The effect is larger at higher interest rates.
Should I adjust for inflation?
Yes — inflation reduces what your money can buy in the future. The “value after inflation” figure shows your final balance in today’s purchasing power, giving you a more realistic picture of your real returns.