An ETF savings plan with 50 euros a month adds up over 40 years to a sum that depends heavily on the return you assume. This guide works through the example, states every assumption and explains why the figure is a calculation rather than a forecast.
Short answer: At 50 euros a month you pay in a total of 24,000 euros over 40 years. Assuming a return of 5 percent a year and 0.3 percent costs, the calculation gives a final capital of roughly 70,600 euros. This is an assumption, not a promise. Last updated: November 2026.
The most important points in brief
- Over 40 years, 50 euros a month adds up to 24,000 euros paid into the plan.
- The final capital depends almost entirely on the assumed return. In the example the range runs from about 43,100 to about 120,700 euros.
- Costs such as fees and spreads reduce the result permanently and belong in every calculation.
- Inflation reduces the purchasing power of the final amount. At 2 percent inflation the real value in the example is about 19,500 to 54,700 euros.
- A calculation does not replace an investment decision or personal advice.
How do you calculate a savings plan over 40 years?
The calculation can be followed in a few steps. It assumes that the same amount is paid in every month and that returns are reinvested.
- Multiply the monthly amount by the number of months: 50 euros times 480 months gives 24,000 euros paid in.
- Divide the annual return by 12 to get the monthly rate. At 5 percent that is about 0.417 percent per month.
- Let each monthly payment earn interest for as long as it stays invested, and add up all amounts.
- Deduct costs as an annual reduction from the return, here 0.3 percent.
Which assumptions sit behind the calculation?
Every figure below rests on the following assumptions. If one of them changes, the result changes too.
- Assumption: the payment is a constant 50 euros a month over 480 months.
- Assumption: the gross annual return is 3, 5 or 7 percent. These are calculation scenarios, not forecasts.
- Assumption: total costs are 0.3 percent a year.
- Assumption: interest is compounded monthly and reinvested.
- Assumption: taxes are not deducted. For the tax treatment, see the saver allowance article linked below.
- Assumption: inflation is 2 percent a year, used only to calculate the real value.
What do the scenarios show?
| Return per year (assumed) | Final capital, nominal | Real value at 2 % inflation | Gain over 24,000 euros paid in |
|---|---|---|---|
| 3 percent | about 43,136 euros | about 19,536 euros | about 19,136 euros |
| 5 percent | about 70,589 euros | about 31,969 euros | about 46,589 euros |
| 7 percent | about 120,688 euros | about 54,658 euros | about 96,688 euros |
The table shows how strongly compound interest grows with time. In the first years the gap between the scenarios is small, after 30 and 40 years it becomes large. That is why the return assumption matters so much.
What does the real value mean?
The real value shows what the final amount is worth in today’s prices. At 2 percent inflation a year, money loses about 55 percent of its purchasing power over 40 years. For this reason the nominal final amount alone is a poor measure for retirement planning.
Which costs should you include?
Alongside the return, costs determine the result. The German consumer organisation Verbraucherzentrale points out that order fees are often low, but costs can arise indirectly through spreads and execution prices. A savings plan also carries the fund costs, which are stated in the product information. An overview of cost types is available from the Verbraucherzentrale on costs and risks of neobrokers (in German).
- Order fees and spreads, meaning the difference between buying and selling prices.
- Ongoing fund costs, which are shown in the product.
- Costs for the custody account or the savings plan, where the provider charges them.
Why the time horizon matters so much
Each payment earns interest for as long as it stays invested. In the example, an amount paid in during the first year works for 40 years, while an amount paid in during year 35 works for only five. An early start gives interest more time, regardless of how high the individual monthly amount is.
The reverse also holds: anyone who starts late has to save considerably more to reach a similar final capital. The calculation makes this effect visible, although it cannot take the personal decision for you.
What the calculation does not show
The calculation contains no price fluctuations. The value of an ETF can fall noticeably in individual years, and a savings plan guarantees no particular result. The point at which you sell also matters. The calculation therefore only shows how interest and costs interact, not what will actually happen.
Frequently asked questions
Is 50 euros a month realistic as a student?
Whether the amount fits your financial plan depends on income and fixed costs. A monthly plan helps you check your room for manoeuvre realistically. The steps are described in Budgetplanung im Studium: Monatsbudget in drei Schritten (in German).
Is a return of 5 percent safe to rely on?
No. In the example, five percent is an assumption and not a promise. Returns fluctuate from year to year, and individual years can be clearly negative. Anyone planning with a calculation should look at several scenarios.
What happens if I pause the savings plan?
A pause reduces the amount paid in and with it the compound interest on those sums. Amounts already invested stay in the custody account. Whether you resume the plan later is a personal decision.
How do taxes affect the result?
Returns from capital investments can be subject to tax. The saver allowance determines how much capital income stays tax free in a year. The rules and the amount are described in Sparerpauschbetrag 2026: Wie viel Kapitalerträge steuerfrei bleiben (in German).
What you can do now
- Set a monthly amount that you can keep up over the long term, including in weaker months.
- Work through the example with your own assumptions for return and costs.
- Compare the costs of providers using their official price lists rather than advertising alone.
- Review the calculation once a year and adjust the assumptions to the actual development.
Related articles
- ETF savings plan for students: how it works step by step (in German)
- Investing as a student: first steps for beginners (in German)
- Budget planning as a student: a monthly budget in three steps (in German)
- Saver allowance 2026: how much capital income stays tax free (in German)
- Money, account and credit: the overview for young adults (in German)
Sources: Verbraucherzentrale, Neobroker: costs and risks of fast securities trading via app (German) (status 03.03.2026). The calculation assumptions are not official values and are marked as assumptions in this article.
Last updated: November 2026. This guide is general information, not individual advice.
