Portfolio milestone tracker — when each round number arrives

One forward pass does the whole thing. The portfolio compounds at the monthly root of your expected return with your contribution added each month, and every time the balance crosses one of the eight thresholds the month is recorded, up to a fifty year limit. Running a single simulation rather than solving eight separate equations is what keeps the timeline internally consistent — every date on it comes from the same path. Thresholds at or below your current balance are marked as already reached rather than being given a date in the past.

Contributions are flat in nominal terms for the whole projection, which understates most careers and overstates none. The return is constant, so the smooth acceleration you see is the model rather than a forecast; a real path crosses a threshold, falls back below it, and crosses again. Nothing is adjusted for inflation, so a million euros thirty years out is a much smaller milestone than a million euros today.

Why is the first hundred thousand the hardest?

Because until the portfolio is large relative to your annual contribution, the growth term contributes almost nothing. The crossover is arithmetic you can do on this page: the portfolio starts pulling its weight when the balance times the return exceeds twelve times the monthly contribution. Below that you are effectively saving in an account that happens to drift upward, and above it the balance grows faster than you can add to it.

Should I set a milestone in real or nominal terms?

The dates here are nominal, so a distant milestone is easier to reach than it looks and less valuable when it arrives. If a milestone is really a proxy for buying something — a house, a year off, an income — then inflate it before setting it, or read the date as optimistic. The purchasing power page converts between the two directly.

Why do the later gaps get shorter?

Because each threshold is roughly a fixed multiple of the one before it, and the time to multiply a balance by a fixed factor shrinks as the contribution becomes a smaller part of the growth. Under pure compounding with no contributions that time would be constant, which is what the rule of 72 page shows; the shortening here is the contribution stream steadily mattering less.

• Contributions versus returns — which built your portfolio
• Rule of 72 — doubling time at any rate of return
• What another 50 euros a month is worth