Compound Interest Calculator
See how your money grows exponentially with the power of compounding
// Compounding Frequency Comparison
Year-by-Year Breakdown
| Year | Deposited | Interest | Total Interest | Balance |
|---|---|---|---|---|
| 📈 Calculate above to see yearly growth | ||||
How Compound Interest Works
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest — which only earns on the original amount — compound interest grows exponentially because your interest earns interest too.
Compound Interest Formula
Compounding Frequency
The more frequently interest compounds, the more you earn. Daily compounding produces slightly more than monthly, which produces more than annual. The difference is small at low rates but becomes more significant over longer periods and higher balances.
The Rule of 72
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 7% interest your money doubles approximately every 10.3 years. At 10% it doubles every 7.2 years.
Why Regular Contributions Matter
Adding regular monthly contributions dramatically accelerates growth. Even small monthly amounts — say €100 per month — can add tens of thousands to your final balance over 20–30 years due to the compounding effect on both the principal and the ongoing contributions.
From the Blog
// Rule of 72
Divide 72 by your rate to find doubling time. 7% → doubles in ~10 years.
// Start Early
Starting 10 years earlier can double your final balance, even with the same total contributions.
// Reinvest Returns
Always reinvest dividends and interest — this is what triggers the exponential compounding effect.
// Real Rate
Subtract inflation from your rate for the real return. 7% nominal − 3% inflation ≈ 4% real growth.