Reach a target amount
How long does it take to reach a target amount with your monthly saving, or which monthly amount reaches it in the years you choose? Pick one of the two questions in the tool.
How long: a worked example
With €5,000 up front, €250 a month and 6% a year, the balance passes €50,000 after 120 months: exactly 10 years. In that month it stands at €50,067, of which €35,000 is what you put in and €15,067 is growth. Adding €50 a month more gets there 14 months sooner.
The “how long” mode has no field for fund costs. With 0.14% ongoing costs taken off (5.86% a year), the same plan takes 121 months and ends at €50,124, with €35,250 put in. To include costs yourself, enter your return minus the fund’s TER. The 6% is an illustrative assumption, not a forecast.
How much per month: a worked example
For €50,000 in 15 years from €0, at 6% a year before costs and 0.14% ongoing costs, the monthly amount is €174 (€173.99 to the cent). Over 15 years you put in €31,318 and growth adds €18,682.
| After | Put in | Balance |
|---|---|---|
| 5 years | €10,439 | €12,096 |
| 10 years | €20,879 | €28,298 |
| 15 years | €31,318 | €50,000 |
How it calculates. Both modes work in monthly steps, with contributions added at the end of each month: new balance = old balance × (1 + r ÷ 12) + monthly amount. In “how long”, r is the return you enter; if you also enter inflation, it becomes the real return (1 + return) ÷ (1 + inflation) − 1, so the target is in today’s money. The tool repeats the step until the target is reached. In “how much”, r is your return minus the ongoing costs, and the tool solves monthly amount = (target − start × (1 + r ÷ 12)n) × (r ÷ 12) ÷ ((1 + r ÷ 12)n − 1), with n the number of months. It rounds up to whole cents and checks the answer month by month.
How to read the result. “How long” shows the time to the target and the balance in the month it is passed, which is a little above the target because months come in whole steps. “How much” shows the monthly amount, what you put in and the growth; the year table shows how the gap closes. The longer the horizon, the more of the work growth does: in the example above it is 37% of the end amount.
What it is not. Not a forecast and not advice. The calculation assumes a constant return, while real markets rise and fall, and it does not say whether a target or a monthly amount suits anyone. Tax and transaction costs are not included. After 60 years the “how long” mode stops.
Where it comes from. Only the formula of the ETF Calculator and your own input. The tool uses no external data and stores nothing.
Two situations with returns you choose
Starting with a small sum. Someone has €2,000, can add €150 a month and wants €30,000. At a chosen 5% a year (no fund costs entered), the balance passes the target after 133 months, about 11 years and 1 month. It then stands at €30,063, of which €21,950 was put in. Adding €50 a month more gets there 26 months sooner. If they also enter 2% inflation, so the target is in today’s money, the return used becomes about 2.94% a year: the same plan then takes 150 months and ends at €30,041, with €24,500 put in, and €50 more a month saves 31 months.
Working backwards from €100,000. Someone wants €100,000 in 25 years and already has €10,000. At a chosen 5% a year before costs and 0.14% ongoing costs, the monthly amount is €113.82. Over 25 years they put in €44,146 and growth adds €55,856. Starting from €0 instead, the monthly amount is €171.47, with €51,441 put in and €48,563 of growth. At a chosen 3% from €10,000, the monthly amount rises to €181.94; at 0%, growth is nil and it is simply €300 a month.
| Return you choose (from €10,000) | Monthly amount | Put in over 25 years |
|---|---|---|
| 5% a year | €113.82 | €44,146 |
| 3% a year | €181.94 | €64,582 |
| 0% a year | €300.00 | €100,000 |
These are illustrations, not forecasts. Real returns vary from year to year and can be negative, and past performance guarantees nothing. The 6% default in the tool is an illustrative assumption, not a forecast.
How the calculation works, step by step
Each month the balance is multiplied by (1 + r ÷ 12) and the monthly amount is added. A one-month example: start €1,000 at a chosen 6% a year, so r ÷ 12 is 0.5%, with €250 added: 1,000 × 1.005 + 250 = €1,255. “How long” repeats this step until the balance reaches the target. “How much” uses the closed formula in the card above and then checks it month by month.
Common mistakes when reading the result
- Treating the answer as a deadline. The result depends on the return and monthly amount you choose, both of which can turn out differently.
- Setting the target without prices rising in mind. A goal in today’s euros may cost more later.
- Assuming steady returns. In real life a month can be negative, which can push the date further away.
What the calculation leaves out
One constant return in every month, with no good or bad years. In real life the order of returns matters: a fall early on hurts a plan more than one near the end, and the tool cannot show that. Tax, transaction costs, changes in your income and any pause in saving are not included either. Whether a target or a monthly amount is sensible for you is not something the tool can say.
Questions about reaching a target
Why is the balance a little above the target?
Months come in whole steps. The tool stops in the first month in which the balance is at or above the target, so it usually ends a bit over it: in the first situation €63 above €30,000.
Why does entering inflation lengthen the time?
With inflation filled in, the target is treated as an amount in today’s money, and only the return above inflation counts. In the first situation that is about 2.94% instead of 5%, so the same plan needs 150 months instead of 133.
Does a monthly amount here mean I should save it?
No. It only shows what the arithmetic needs at the return you chose. It is a worked example, not advice, and a lower or negative return would need a larger amount.
Further reading: