Picture a kitchen table on a Sunday afternoon. A bank statement, a phone with the calculator open, and a question that sounds simple: if I put 200 € aside every month, what will I actually have one day?
You type 200 × 12 × 30. You get 72,000 €. And you know that number is wrong. It’s missing the part that matters most — the money your money earns.
That is what the Savings Calculator is for. Not a spreadsheet you have to build. Not an app you have to install. A page you open, fill in, and understand.
The number your phone calculator can’t show you
Let’s stay with that example: 200 € a month, 5 % interest per year, for 30 years.
Your own deposits add up to 72,000 €. The calculator shows an end balance of about 167,145 €. The difference — roughly 95,000 € — is interest. More than half of the final amount is money you never paid in.
The chart makes this visible. Your starting capital, your deposits and your interest each get their own colored layer. In the early years, the interest layer is a thin line. Then it starts to thicken. Around year 15, the interest you earn in a single year overtakes the 2,400 € you pay in. From then on, your money is working harder than you are.
That is the compound interest effect. Interest that stays invested earns interest of its own. Slowly at first, then all at once.
Five questions, one calculator
A savings plan has five moving parts: what you start with, what you add regularly, the interest rate, the duration — and what you end up with. Know any four, and the calculator finds the fifth.
How much will I have? That’s the classic case. Enter your starting capital, savings rate, interest and duration, and you get your final capital.
How much do I need to save each month? Say you want 100,000 € in 20 years. At 5 %, the calculator tells you it takes about 242 € a month. This is the savings rate mode — probably the most useful one, because it turns a vague wish into a monthly number.
How long will it take? Keep saving 200 € a month at 5 %, and you reach 100,000 € after about 22 years and 7 months. The duration mode answers the question “when?”
What return do I need? If your plan only works with an unrealistic interest rate, it’s better to find out now. The interest rate mode shows the annual return your money must earn to reach your goal.
How much do I need to start with? Maybe you have a lump sum — an inheritance, a bonus, savings from an old account. The initial capital mode tells you how big that one-time deposit must be today.
What you fill in
Each field is one decision in your plan:
- Initial capital — the amount you invest once, on day one. Starting from nothing? Enter 0 €.
- Savings interval — how often you pay in: monthly (the default) or yearly.
- Savings rate — how much you pay in each time.
- Compounding interval — how often interest is credited and starts earning interest itself: monthly or yearly.
- Interest rate p.a. — the expected annual return before taxes.
- Duration — how many years the plan runs.
- Taxes — optional. More on that below.
The cost of waiting
Here’s the comparison that changes how people think about saving.
Person A saves 200 € a month for 30 years. Person B waits ten years, then tries to catch up with 300 € a month for 20 years. Both pay in exactly 72,000 €.
Person A ends with about 167,000 €. Person B ends with about 124,000 €.
Same money in. Over 40,000 € less out. The only difference is time. The calculator lets you try this with your own numbers — and that tends to be more convincing than any advice.
Taxes, honestly
A savings plan that ignores taxes looks better than it is. Switch on taxes and the calculator applies German capital gains tax: 25 % plus the 5.5 % solidarity surcharge, 26.375 % in total.
It also accounts for the things that reduce that tax:
- The tax-free allowance (Sparer-Pauschbetrag) — for example 1,000 € a year for single persons.
- The partial exemption (Teilfreistellung) for funds — for example 30 % for equity funds, meaning that share of the gains stays tax-free.
How the tax hits depends on the type of investment:
- Distributing — every interest payment is taxed right away, and only the net amount is reinvested. The allowance renews every calendar year.
- Accumulating — all gains stay invested. Tax is due once, at the end, on the total gain, with the allowance applied once. (The Vorabpauschale is not modeled.)
In our example — 200 € a month, 5 %, 30 years, an accumulating equity fund — taxes take about 17,300 €, leaving roughly 149,800 €. Less than before, but still more than twice what you paid in.
A calculator should calculate
Everything runs in your browser. No sign-up, no account, nothing stored on a server. You can change a number and watch the chart react instantly — which is the whole point. Planning is not one calculation. It’s trying ten versions until one feels right.
Frequently asked questions
What can I calculate with a savings calculator?
Any one of the five parts of a savings plan: the final capital, the starting capital, the monthly or yearly savings rate, the interest rate you need, or how long it will take to reach your goal.
How much should I save each month?
A common rule of thumb is 10 % to 20 % of your monthly net income. Before you start, cover your fixed costs and build an emergency fund of three to six months of expenses in an easily accessible account.
When does compound interest really kick in?
Over long horizons. In our example, the yearly interest overtakes the yearly deposits after about 15 years. The longer you stay invested, the steeper the curve gets.
Does monthly or yearly compounding make a difference?
Yes, but a small one. With monthly compounding, interest is credited sooner and starts earning interest earlier, so the end result is slightly higher.
How are taxes calculated?
With taxes switched on, the partial exemption is applied first — for equity funds, 30 % of the gains stay tax-free. The rest is offset against the tax-free allowance. Only what’s left above that is taxed at 26.375 %. Distributing investments are taxed on every interest payment; accumulating investments are taxed once at the end of the term.