About and calculation methodology

Who is behind the tools

The project is maintained through its public GitHub repository. You can inspect the implementation, see the contribution history, and raise questions with the maintainers there. This site does not claim professional financial accreditation or independent expert certification.

There is no login or paid advisory service. Calculator outputs are educational estimates, not investment recommendations, loan offers, insurance quotes, or instructions for filing a tax return.

What the calculation engine assumes

Investment returns are annual effective rates. Monthly tools convert them using (1 + annual rate)^(1/12) - 1. Monthly investment contributions occur before that month's growth; withdrawals occur before growth on the remaining balance. Loan rates are nominal annual rates divided by 12, with instalments paid at month end.

Today's-money values divide a future amount by (1 + inflation)^years. Currency selection changes formatting and the scale of untouched default inputs; it does not convert an existing amount at an exchange rate. Shared scenarios specify their currency and inputs in the URL.

The calculator's formula panel states its specific assumptions. Tax is excluded outside dedicated tax models. Fees, changing market returns, daily interest, and individual circumstances are included only where the tool explicitly models them. A steady return projection is not a prediction.

Verification and rule-dependent estimates

The source includes automated tests for the finance functions, including cash-flow conservation, zero-rate cases, and comparisons between closed-form formulas and simulations. Tests help catch implementation errors; they do not establish that a market assumption or tax treatment applies to you.

Country-specific models identify the tax year or scheme rules they use. Check the applicable official authority and your provider before acting, especially when allowances, rates, eligibility, or legislation change. A dated model is not a substitute for an official assessment. The source files expose the rule constants and model exclusions.

Editorial scope and corrections

Practical guides explain concrete decisions with reproducible examples and distinguish assumptions from outcomes. Their publication dates describe the guide, not an expert review of every calculator. Source links provide background or rules; they are not endorsements.

For a suspected error, report the page URL, the input assumptions, the expected result, and a supporting calculation or official source. Do not include identifying account details. Corrections can be tracked in the repository's issues and change history. The guides are currently English-only; calculator interfaces support six languages.

Found an error? Report a correction on GitHub. Include the page and assumptions, but do not post private financial information.

Advertising and privacy

Google AdSense may fund the site when ad serving is approved and configured. Advertising is separate from calculator results and is not an endorsement of an advertised product. No manual ad units are enabled by default in the source.

Calculations run locally, but scenario inputs appear in the URL. Shared links reveal those inputs, and URLs may be available to hosting or third-party services. Avoid entering private identifying information. Read the privacy policy for local storage, hosting, advertising, and consent information.