Compound Interest Calculator
See how savings grow with compound interest — annual, monthly or daily compounding, with optional regular contributions.
Last updated: April 2026 · Runs in your browser · No sign-up
Endkapital
144.572,72 €
Why start early
At 7% annual return, €100/month starting at 25 reaches ~€264k by 65. The same €100/month starting at 35 reaches only ~€122k. Ten years of compounding more than doubles the outcome, even with identical monthly contributions. Time beats timing.
What to plug in
- Principal — starting balance.
- Rate — expected annual return (stocks ~7% real, savings ~2%).
- Term — years until you need the money.
- Contribution — regular deposit each month or year.
Frequently Asked Questions
How does compound interest work?
Interest is added to the principal each period, so the next period's interest is calculated on a larger balance. Over 10–30 years this creates exponential growth, not linear.
How often should interest compound?
More frequent compounding marginally increases returns. Daily vs annually compounding at 5% over 20 years differs by about 2.5%. The compounding frequency advertised by a bank matters less than the nominal rate.
What's the rule of 72?
Quick mental maths: years-to-double ≈ 72 ÷ interest rate. At 6%, money doubles every ~12 years. At 9%, every ~8 years. Great for back-of-napkin comparisons.
Does the calculator account for inflation or taxes?
Not automatically — it shows nominal returns. Subtract your local inflation rate for real returns; subtract capital gains or interest tax for post-tax returns.