Methodology: how our calculators are built
Open formulas instead of a black box
Every calculator page shows the formula it uses, an explanation of all variables and the calculation conventions (for example, how contributions made during the year are compounded). You can reproduce every result with a pocket calculator or a spreadsheet – the worked examples on each page demonstrate this step by step.
Separate, tested calculation logic
The calculation of each calculator is a stand-alone program module with no connection to the user interface. Each module passes at least five automated tests, including edge cases (zero values, extreme values, invalid inputs) and control calculations against reference values that were derived independently using closed-form formulas. If a test fails, nothing is published.
Example assumptions instead of “current values”
Our calculators deliberately do not know any current market rates, prices or product terms. You enter all the decisive assumptions (interest rate, return, inflation rate, terms) yourself. Pre-filled numbers are explicitly marked as an example assumption, so no value can be mistaken for a researched market value.
Assumptions, limits and review date on every page
Every calculator visibly states its assumptions, its limits and a calculator-specific note on what it is not suitable for. Each calculator page also shows the date of its last technical review.
Privacy by architecture
All calculations run entirely in your browser. Your inputs are not stored, not transmitted and not analysed. The website works without an account, without cookies and without tracking.
What we do not do
We do not give investment, tax or legal advice, do not recommend products, banks or brokers, do not show price forecasts and do not arrange loans or insurance. Our calculators are neutral model calculations – you make decisions yourself, with expert support where needed. Details:legal notice.