How much do I need to save each month?
Name a target and a deadline. Get the monthly figure that reaches it under each return assumption.
The number you want to reach.
A starting point, not a forecast.
More options(3)
Charges reduce the return, so they raise the monthly figure.
Save this much every month
$321
To reach $100,000 in 15 years, you would put in $321 a month — $57,858 of your own money in total — and rely on growth for the remaining $42,142. That is if returns average 7% a year. At 4% it would take $409 a month instead.
- Monthly amount
- $321
- Your money, in total
- $57,858
- Growth doing the rest
- $42,142
If returns average…
Nobody knows which of these happens
| Assumption | Monthly amount needed |
|---|---|
| 4% a year — cautious | $409 / mo |
| 7% a year — middle | $321 / mo |
| 10% a year — optimistic | $251 / mo |
Markets do not return the same amount every year. The band shows the same plan under three different assumptions, so you can see how much the answer depends on a number nobody knows.
The growth calculator, run backwards
The growth calculator asks what a contribution becomes. This one asks the reverse: given the destination, what does the contribution have to be? It is the same arithmetic solved for a different unknown, so the two pages will always agree — put the monthly figure from here into that page and you will land on your target.
Read the cautious row first
There is an inversion here that catches people out. In every other tool on this site, the optimistic scenario produces the nicest number. Here it produces the smallest monthly figure — because if markets are generous, you need to contribute less.
That makes the optimistic row the dangerous one to plan around. Saving the amount that only works if returns come in at the top of the range means finding out you were short at exactly the point it is too late to fix. The cautious row is the one that survives being wrong.
Time is doing more work than the monthly amount
Drag the deadline slider before you drag anything else. Adding five years to the horizon usually cuts the required monthly figure far more than any plausible change to the assumed return does, because those extra years compound every contribution that came before them. If the number the tool gives you looks impossible, the horizon is almost always the more workable lever than the rate.
What to do if the figure is out of reach
Nothing on this site will tell you to spend less or earn more. What the tool can honestly show you is the trade-offs, and they are worth playing with directly: lengthen the deadline, lower the target, or accept that the plan only works under a return assumption you may not want to bet on. Seeing which of those three moves the number most is genuinely useful. Which one you pick is not an arithmetic question.
It is also worth checking the monthly figure against what actually arrives rather than against your salary. The take-home pay calculator shows the difference, which on most salaries is large enough to change whether a target looks reachable.
Common questions
Why does the monthly figure fall when I raise the assumed return?
Does it account for the money I have already saved?
Should the contribution rise over time?
Not advice. This tool applies arithmetic to assumptions you entered. It does not know your circumstances, your tax position or your goals, and it is not a recommendation to buy, sell or hold anything. Past returns do not predict future ones, and no figure here is a forecast.