Savings Goal Calculator
Enter your savings goal and find out how much you need to contribute each month to reach it within your chosen timeframe.
Results
Required monthly contribution
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Total contributed
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Interest/return earned
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Monthly contribution = (savings goal ∑’ initial capital — (1 + r)^n) · [((1 + r)^n ∑’ 1) · r], where r is the monthly return and n the number of months. At 0% return, the contribution is simply (goal ∑’ initial capital) · n.
Your initial capital already reaches (or exceeds) your goal at this return and timeframe! You don't need to contribute anything more.
Savings projection
When should you use this calculator?
This calculator solves the reverse problem of compound interest: instead of projecting how much you'll have by saving a fixed amount, it calculates how much you need to contribute each month to reach a specific goal within a given timeframe.
How it is calculated
The formula solves for the required monthly contribution: contribution = (goal ∑’ initial capital — (1 + r)^n) · [((1 + r)^n ∑’ 1) · r], where r is the monthly return and n the number of months in the timeframe. First it calculates how much the initial capital alone will have grown by the end of the period; the difference between the goal and that figure is what the monthly contributions need to cover, spread using the same annuity factor used in compound interest.
Practical example
A numeric example: to reach a €20,000 goal in 5 years, starting with €2,000 already saved and an expected 3% annual return, the initial capital alone would grow to €2,323.23, so the required monthly contribution is €273.44. A total of €18,406.19 would be contributed over the timeframe, and the remaining €1,593.81 towards the goal would come from interest earned. With no return at all (0%), the required monthly contribution would rise to exactly €300: the expected return reduces the monthly saving effort by about €26.56.
Legal and tax context
The return you use should match the type of product you're saving in: a savings account or deposit offers lower, more stable returns, usually between 0% and 3% a year with very low risk, while an index fund or a diversified portfolio can offer higher long-term returns in exchange for more risk and short-term volatility. Using an optimistic return from a risk product for a short-term goal, or one with no margin for error, can lead to underestimating the monthly contribution actually needed.
This calculator solves the reverse problem of the compound interest calculator: instead of projecting forward how much capital you'd get with a fixed contribution, it calculates the contribution needed to reach a specific goal within a given timeframe. The result is a mathematical estimate based on a constant return that varies in practice, and it is not financial advice nor a guarantee the goal will be reached exactly within the projected timeframe.
Common mistakes
A common mistake is not accounting for the fact that the initial capital also grows over time, and calculating the monthly contribution by simply dividing what's left to reach the goal by the number of months, without subtracting that growth. Another frequent mistake is assuming the monthly contribution will stay constant throughout the timeframe: if it actually varies (for example, it's reduced in some months), the real time needed to reach the goal will also differ from the initial estimate.
Practical tips
If your goal is a fixed amount in today's money (for example, the current price of a home down payment), it's worth remembering that inflation reduces its future purchasing power: you can increase the goal according to expected inflation, or use a return net of inflation directly in the calculation. As a general planning rule (the well-known 50/30/20 rule splits 50% of income into essential expenses, 30% into discretionary spending and 20% into savings), the sooner you start saving and the longer the available timeframe, the lower the monthly contribution needed for the same goal, thanks to compound interest working on the capital already accumulated.
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Frequently asked questions
How is the required monthly savings amount calculated?
It starts from the savings goal and subtracts the future value of the initial capital already invested; the remainder is spread across monthly contributions that, at the given return, reach exactly the goal by the end of the timeframe.
What if my initial capital is already enough?
If the initial capital, grown at the given return over the timeframe, already reaches or exceeds the goal, the calculator shows that you don't need to contribute anything more.
What return should I use for a savings account versus investing?
A savings account or deposit typically offers 0-3% a year with very low risk. A diversified investment portfolio can return more over the long term, but with short-term value fluctuations.
Is this the same as the compound interest calculator?
Not quite. The compound interest calculator projects forward how much you'll have with a fixed contribution; this one solves it backwards, calculating the contribution needed to reach a specific goal.
How does inflation affect my savings goal?
If your goal is a fixed amount in today's money, inflation will reduce its future purchasing power. To account for it, you can increase the goal based on expected inflation, or use a return net of inflation.
What if I change my monthly contribution partway through?
This calculator's result assumes a constant contribution throughout the whole timeframe. If your actual contribution varies, the time needed to reach the goal will also differ from the initial estimate.
How much does the expected return reduce my required monthly contribution?
It depends on the timeframe and return, but the effect is real: in this guide's example (€20,000 goal, €2,000 initial, 5 years), going from 0% to 3% annual return reduces the required monthly contribution from €300 to €273.44.
What happens if I extend the timeframe to reach the same goal?
A longer timeframe reduces the required monthly contribution, because the capital has more time to grow and the contributions are spread over more months. It's the same principle as in the compound interest calculator: time matters more than the amount contributed each month.
Should I use the return of a savings account or a riskier investment?
It depends on your risk tolerance and timeframe: for short-term goals or ones with no margin for error, a conservative return (savings account or deposit) is safer; for long-term goals, a diversified portfolio can offer a higher expected return in exchange for short-term volatility.
Does this calculator account for inflation on my savings goal?
Not automatically. If your goal represents today's price for something, it's worth increasing it according to expected inflation over the timeframe, or using a return net of inflation in the calculation to get a more realistic monthly contribution.