Model Example: A Couple Saves €100 a Month. The Numbers at 5, 10 and 20 Years

VESTELON FLOWAugust 2, 20267 min read

This is a model example, not the story of a real couple and not a promise of returns. It shows one single thing: what happens when two people find €100 a month in their accounts and put it aside regularly. Every number in this text can be recalculated by you, the formula is below.

Why exactly €100? Because for many households that amount does not have to come out of the salary or the standard of living. It often hides in the leak: forgotten subscriptions, overlapping services and fees nobody reads.

The setup of the model example

Jana and Martin are an invented couple used for illustration. They agreed on three rules:

they put aside €100 at the end of every month, without exception,
they never increase the amount, although in reality they could over time, the model is deliberately conservative,
they do not touch the money, no withdrawals for the whole period.

We compare three routes for the same hundred: a current account with no interest, a savings account at 2% a year, and investing at an illustrative 7% a year. In all cases the return is compounded monthly.

Where to find the €100 so it does not hurt

The most common objection is: we have nothing left to save. Yet the data shows many households have no idea what they pay in recurring charges. A 2022 survey by C+R Research found that American consumers estimated their monthly subscription spending at $86, while in reality they paid an average of $219, roughly 2.5 times their own estimate.

In our model example, Jana and Martin assembled their €100 like this (the amounts are indicative, illustrative):

€35: three subscriptions neither of them had opened in three months,
€25: two streaming services and a cloud plan whose features overlapped,
€12: account and card fees that dropped after switching to a different banking plan,
€28: an old mobile tariff and an insurance policy that got cheaper after one phone call.

Not a single euro came out of food, housing or time with the kids. The whole €100 came from payments that gave them nothing.

Option A: the hundred stays in the current account

A current account pays practically 0% interest. Only the deposits add up:

after 5 years: €6,000,
after 10 years: €12,000,
after 20 years: €24,000.

It is an honest reserve and better than nothing. But it has a weakness: with inflation, the purchasing power of this money falls over the years. The nominal number grows, yet it buys less and less.

Option B: a savings account at 2% a year

The 2% rate is illustrative, banks change it over time. With monthly compounding, before tax on interest, the result is:

after 5 years: €6,305 (deposits €6,000),
after 10 years: €13,272 (deposits €12,000),
after 20 years: €29,480 (deposits €24,000).

Over two decades the interest added €5,480. Not nothing, but the curve is still almost a straight line.

Option C: investing at an illustrative 7% a year

The third route is regular investing, for example into a broad index fund. (The return of about 7% a year is only illustrative, roughly a long-run average of stock markets. Past performance does not guarantee future results, the value of an investment can also fall, and this text is not financial advice.) With monthly compounding it comes to:

after 5 years: €7,159 (deposits €6,000),
after 10 years: €17,308 (deposits €12,000),
after 20 years: €52,093 (deposits €24,000).

For the first five years the difference versus the account is boring: only €1,159. After twenty years the same hundred a month is worth €28,093 more than the couple actually paid in. More than half of the final sum is returns, not deposits.

The whole comparison in one place

After 5 years: current account €6,000, savings €6,305, investing €7,159.
After 10 years: current account €12,000, savings €13,272, investing €17,308.
After 20 years: current account €24,000, savings €29,480, investing €52,093.

The model teaches two lessons. First, time decides: the differences are laughably small at the start, and that is exactly when most people give up. Second, where the money sits decides: the same discipline, the same couple, and after 20 years a €28,093 gap between the current account and investing.

How to repeat the calculation

We used the standard future value formula for a regular deposit at the end of the month:

FV = deposit × ((1 + r)^n - 1) / r

r = annual return divided by 12. For 7%: 0.07 / 12 = 0.0058333.
n = number of months. For 20 years: 240.

Check for 20 years at 7%: (1.0058333)^240 = 4.0387. Then (4.0387 - 1) / 0.0058333 = 520.9, and multiplied by the €100 deposit it gives €52,093. Small rounding differences can shift the result by a few euros, but the logic holds in any spreadsheet or calculator.

Where to find your own €100

The model stands or falls on the first step: finding the hundred that leaks away today with nothing in return. Going through statements by hand works, but takes hours. The faster route: upload one bank statement at app.vestelonflow.com, the VESTELON FLOW analysis runs in your browser and you see your recurring payments sorted in about a minute. No account and no bank login needed, and nothing leaves your device without your consent.

And if a hundred feels too small, try the approach from how to find €300 a month. The principle is the same, you just dig deeper. The model couple in this text started at €100. More important than the exact amount is that yours starts this month.

Upload one bank statement. FLOW shows exactly where your money leaks today, what it is worth once you redirect it, and the year it could set you free. Not another tracker: a plan you can act on.

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