How much you need to invest each month to reach £1m depends on four things: what you have already invested, how long you have, how much you can contribute, and the return you assume.
There is no honest single answer. Anyone giving you one without asking those questions is skipping the part that matters.
That is why I built the £1m Path Calculator. It lets you put your own starting amount, monthly contribution, time horizon and illustrative annual return into the calculation without storing any of your information.
Start with the target, then work backwards
A £1m portfolio can sound so large that it becomes an abstraction. Working backwards makes it more useful. Rather than asking whether £1m is realistic in the abstract, ask what combination of time, contribution rate and starting capital would make it possible under a range of assumptions.
The three levers are simple:
- Starting capital: money already invested has more time to compound.
- Monthly contribution: a sustainable contribution matters more than a short burst of enthusiasm.
- Time: starting earlier gives compounding more room to work.
Why the monthly contribution matters
Your contribution rate is the part of the calculation you can influence most directly. Markets will not deliver the same return every year, but you can decide how much of your income is consistently directed toward future freedom.
That does not mean the answer is to make life miserable in pursuit of a number. A contribution rate only works if it is sustainable through normal life, unexpected costs and changes in work or family circumstances.
Use more than one return assumption
A calculator can be useful without pretending to forecast the future. I prefer looking at several illustrative return assumptions and asking what happens if reality is less generous than the optimistic case.
The calculator uses monthly compounding with end-of-month contributions. It excludes tax, fees, inflation and market volatility, so its result is an illustration rather than a promise. That limitation is a feature. It keeps the focus on the inputs you can control.
The cost of delaying
The most useful number is often not the final total. It is the difference between starting now and starting five years later with exactly the same monthly contribution. Time is not exciting, but it is difficult to replace once it has gone.
If £1m is not the target that matters to you, change it. The aim is not to copy somebody else’s number. It is to build enough assets to create more options over your own time.
Use the calculator as a planning tool
Try three versions of your plan:
- A cautious case with a lower illustrative return.
- A base case using a contribution rate you can genuinely maintain.
- An accelerated case that shows what would change if income or contributions rise.
Then focus on the habits behind the numbers. The route to financial independence is usually less about finding a perfect forecast and more about building a process you can keep following.
Use the free £1m Path Calculator, or read more about the personal side of financial independence.
This article and calculator are for education only. They are not personal financial advice and do not predict investment returns.