What the €100-a-Month MSCI World Calculation Actually Shows

The calculation behind the headline starts with a simple savings plan: €100 invested every month for 30 years in an MSCI World index fund. At the index's historical return of 8.41% since its 1970 launch, the nominal balance would reach €153,275.90.

That figure falls quickly once real-world deductions are applied. After German taxes, including the partial exemption for equity funds, the balance becomes €131,624. Adjusting for inflation at the European Central Bank's 2.0% target leaves only €72,666 in current purchasing power. Using Germany's average inflation rate of 2.7% since the index launched reduces it further to €59,186.

The resulting real return is roughly 3.1% per year, not the 8.4% often quoted. The point is not that an MSCI World savings plan is a bad idea, but that investors should avoid doing their planning with the nominal number. Other low-risk alternatives such as call money are not presented as better options, because their returns after inflation can be negative.

Why the MSCI World’s 8.4% Headline Return Shrinks to 3.1%

The gap between 8.4% and 3.1% is not a forecasting error

The difference comes from three compounding effects: the nominal return is measured before tax, the after-tax figure still does not reflect lost purchasing power, and the inflation assumption matters enormously. The article's two inflation scenarios—2.0% and 2.7%—change the real value of the final balance by more than €13,000, which shows how sensitive long-term wealth calculations are to even small inflation differences.

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What this does to the “get rich with ETFs” assumption

For a German saver using the historical 8.41% nominal return, the real outcome of €59,186 in current purchasing power after 30 years is far less dramatic than the €153,275.90 nominal headline. That does not mean the MSCI World is unsuitable; the article argues it is still a reasonable long-term strategy. But it means the path to building meaningful wealth through equities is slower in real terms than a simple index chart suggests.

The fee point is a return point

Because the real margin after tax and inflation is already modest, broker fees and product costs directly reduce the final real balance. The article's emphasis on comparing deposit and broker costs is therefore not a side note: in a 3.1% real return environment, an avoidable cost of even a few basis points per year matters more than in a high-return scenario.

How German ETF Savers Can Use the 3.1% Real Return

  • Use 3.1%—not 8.41%—as the planning number when modelling a long-term MSCI World savings plan in Germany. At the article's €100 monthly assumption and 2.7% inflation, the 30-year balance equates to about €59,186 in current purchasing power, not €153,276 nominal.
  • Model your savings target in real euros. If German inflation averages 2.7% rather than the ECB's 2% target, the same nominal balance loses more than €13,000 of purchasing power.
  • Check that your ETF receives the German equity-fund partial exemption used in the €131,624 after-tax calculation. A product or wrapper that does not qualify would leave a lower after-tax result.
  • Treat broker and custody fees as part of the return calculation. Compare low-cost providers for your ETF savings plan, because fee differences directly reduce the already modest real return.