Compound interest calculator
How much savings grow with monthly contributions and an assumed return, also in today's euros.
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Result
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Calculation version: personal@1.0.0. The calculation runs in your browser: we don't send or store the amounts you enter. We only count, without identifying you, that the tool has been used.
How to use it
- 1Enter the capital you start with, what you'll contribute each month and an annual return net of fees (an assumption, not a forecast).
- 2Add the inflation you assume to see the result in today's euros.
- 3Try several returns: the result is very sensitive to it and to the term.
How it calculates
- Equivalent monthly rate: rₘ = (1 + r)^(1/12) − 1.
- Each month: balance = balance × (1 + rₘ) + contribution (the contribution is made at the end of the month).
- Today's euros = final balance / (1 + inflation)^years.
Verifiable example
With €5,000 to start, €200 a month, 4% a year and 20 years: €53,000 is contributed and the final balance is €83,723.96 (€30,723.96 of gains). With 2% inflation, that's €56,343.83 in today's money.
Limitations
- Real returns vary from year to year; here they're assumed constant.
- It doesn't include tax on the gains.
- It isn't investment advice.
What the paid levels will add
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Indicative result
It doesn't constitute financial, tax or investment advice. Check important decisions with a professional.