The two parts of "€3,000 a month"
Turning investments into €3,000 a month is two questions, not one. First: how big a portfolio produces that income safely? Second: how do you build a portfolio that size? Answer them in order.
Step 1: the portfolio behind €3,000 a month
€3,000 a month is €36,000 a year. Under the 4% rule — draw 4% in year one, then track inflation — the portfolio you need is your yearly income divided by 4%. That is €900,000. A quick shortcut gives the same answer: multiply the monthly income by 300, because 12 ÷ 4% is 300, and €3,000 × 300 is €900,000.
Why the rate you pick moves the target
If you retire early or want more safety, a 3.5% rate is more cautious — but it raises the target to about €1,028,571 for the same €3,000 a month. That extra €128,000 is the cost of dropping the withdrawal rate half a point. Pick the rate first; it decides the number you are aiming at.
Step 2: building the €900,000
You reach a big number through regular investing and time, not a single windfall. Each contribution earns a return, and those returns earn returns of their own — compounding — so the amount you invest matters less than how many years it compounds. Starting earlier does more than saving more later.
The compound interest calculator shows what a monthly contribution grows into over your timeline, so you can find the combination of amount, years and return that reaches €900,000.
Run your own numbers
Set your target income and withdrawal rate in the retirement target calculator to fix the portfolio you need, then use the compound interest calculator to plan the monthly investment that gets you there. For the rule behind the target, read the 4% rule explained.