The key idea
Set a target and deadline, subtract the savings already allocated to the project, and calculate a monthly contribution. Start with no investment return so that potential gains remain an explicit assumption.
Give the project a target and deadline
“Save more” is difficult to measure. “Reach €20,000 in five years with €5,000 already set aside” gives you a contribution to calculate and progress to track.
Keep this pot separate from emergency funds. AMF explains that a savings objective should be considered alongside the investment horizon, access to the money and acceptable risk.
Source : AMF — Définir son objectif d’épargne (in French)
A flexible deadline and an unavoidable payment on a fixed date impose different constraints.
Start with a zero-return scenario
The gap between €5,000 and €20,000 is €15,000. Over 60 months, that means €250 a month with no fees or interest. This baseline is easy to compare with actual spending.
If €250 is too much, test a smaller target or more time. With the same initial savings, €15,000 over 72 months is approximately €208.33 a month, with a small final adjustment for rounding.
| Assumption | Value |
|---|---|
| Starting savings allocated to the goal | €5,000 |
| Remaining amount to save | €15,000 |
| Time available | 60 months |
| Monthly contribution | €250 |
| Final balance | €20,000 |
Make the return assumption explicit
Compound interest means retained gains can earn further gains. To compare simulations, specify the rate convention, compounding frequency and contribution timing.
Starting with €5,000 and adding €250 at each month-end, a constant hypothetical effective annual return of 3% produces approximately €21,942 after five years. This uses an equivalent monthly rate of (1.03)^(1/12) − 1 and excludes fees and tax.
That is a mathematical scenario, not a promised outcome. Actual investments can lose value. To reproduce this example, select 3% a year, annual compounding and monthly contributions at the end of the period.
Retain the 0% scenario as a baseline and compare several assumptions rather than selecting a product on its advertised return alone.
Allow for prices and review the plan
A goal priced in today’s money may cost more in five years. At a hypothetical 2% annual price increase, a €20,000 project would cost approximately €22,082. This is an illustration, not an inflation forecast.
To reach that revised target with €5,000 initially and no investment return, monthly saving over 60 months would rise to about €284.70. Regular contributions do not remove the need to review the target itself.
Revisit the plan when income or the project changes: check the actual balance, months remaining and updated cost. If a contribution is missed, spread the shortfall over the remaining period rather than assuming higher investment returns will make up for it.
- Set contributions that also leave room for annual expenses.
- Track project savings separately from emergency funds.
- Adjust the target, deadline or contributions when assumptions change.
Before you take the next step
- My goal has an amount and deadline.
- My starting balance excludes emergency funds.
- I tested a zero-return scenario.
- I understand the assumptions, fees and limits of my simulation.
Try your own numbers
Terms in this guide
Educational content. Examples are illustrative and simulations are not personalised advice.