Savings Goal Calculator
Find how much to save each month to reach a goal by a target date, working in both directions — and what to do when the number is unaffordable.
needed per month
Halving the time nearly triples the payment
The intuition is that saving for ten years instead of twenty means paying twice as much a month. It does not. To reach $100,000 at 6%:
| Years | Monthly | You pay in | Growth | Growth share |
|---|---|---|---|---|
| 40 | $50.21 | $24,103 | $75,897 | 76% |
| 30 | $99.55 | $35,838 | $64,162 | 64% |
| 20 | $216.43 | $51,943 | $48,057 | 48% |
| 15 | $343.86 | $61,894 | $38,106 | 38% |
| 10 | $610.21 | $73,225 | $26,775 | 27% |
| 5 | $1433.28 | $85,997 | $14,003 | 14% |
Twenty years to ten is a factor of 2.82, not 2. You are not only losing half the months; you are losing all the growth those months would have produced, and at long horizons the second loss is the larger one. The penalty is steepest from the longest horizons, where there was most growth to give up.
The control makes it unmistakable. Run the same table at 0% and it is exactly linear — $416.67 for twenty years, $833.33 for ten, $1666.67 for five, doubling every time. Every bit of the non-linearity above is the compounding.
Whose money ends up in the account
The same table read the other way is the more useful version. Of the $100,000 sitting there at the end, over 40 years 76% is money you never earned — you paid in $24,103. Over 5 years only 14% is, and you paid in $85,997.
That is the entire argument for starting early, stated as a number rather than as advice. The growth share falls without exception as the horizon shortens, and it falls fast — which is why an extra decade at the beginning is worth more than a much larger contribution later.
It also reframes what the monthly figure means. At forty years you are buying a small stake in a long compounding; at five you are essentially just saving the money, and the interest is a rounding error on the total.
When the account starts outearning you
On the thirty-year plan — $99.55 a month — the interest earned in a single month first exceeds the contribution made that month at month 140, which is year 11.7.
Before that point you are the main source of the balance; after it the account is, and the gap widens every month from there. Nothing happens at month 140 — it is simply where two smoothly moving quantities cross — but it is a long way in, more than a third of the term at this rate.
And at 0% it never happens at all, which is the same control from the other direction: the crossover is not a feature of saving, it is a feature of the growth. If your money is in something that does not grow, you are the only source it will ever have.
How to use
- Enter your goal amount and target date.
- Add anything you have already saved.
- Read the monthly amount required.
- Adjust the date or the goal if the figure is unrealistic.
Frequently asked questions
What if the monthly figure is impossible?
Then something has to change, and it is better to find out now. The three levers are the amount, the date and the contribution — extending the deadline usually moves the monthly figure most, and shrinking the goal is the honest option when the deadline is fixed.
Should I count investment growth toward a savings goal?
It depends entirely on the timescale. For a goal within a few years, no — money you will need soon should not be exposed to market movement, because a bad year immediately before you need it is not recoverable. For goals a decade out, growth is a reasonable part of the plan.
Where should short-term savings sit?
Somewhere accessible and not exposed to market risk. Interest is a secondary consideration to certainty when the money has a job on a known date, and the difference between a good and a poor savings rate is small compared to the risk of a 20 per cent fall at the wrong moment.
Does automating the transfer help?
Substantially, and this is one of the better-supported findings in personal finance. Money moved automatically on payday is saved far more reliably than money intended to be saved from whatever is left, because whatever is left is reliably less than expected.
Should I save or pay down debt first?
Generally, clear high-interest debt first, since the guaranteed return of not paying interest usually exceeds anything savings will earn. The common exception is keeping a small emergency buffer, because without one the next unexpected expense goes straight back onto the card.
Is this financial advice?
No. It is arithmetic on figures you supply. What is right for your situation depends on your income, obligations and priorities, none of which a calculator knows.
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