About this site
FinancialHelper.Online is a personal project: free financial calculators, no sign-up, nothing to sell. This page explains who is behind it, on what basis the figures are calculated and what they deliberately do not do, so you can judge for yourself how much weight to give them.
Who is behind it
It is maintained by Mario Martínez (mario.computer) in a personal capacity. It is not a company, a financial institution or an advisory firm, and it is not affiliated with any bank, lender or distributor of financial products. There are no clients, no book of business and nothing being sold to you.
How the figures are calculated
The calculators apply standard financial formulas, with no proprietary models and no hidden assumptions. Specifically:
- Amortization. French system using the annuity formula; German system with constant principal; American system with a single principal repayment at maturity. Interest for each period is always calculated on the outstanding balance.
- Savings. Future value of a lump sum plus a monthly annuity, with the nominal rate converted to an equivalent monthly rate via the effective annual rate, so the compounding frequency you choose genuinely changes the result.
- Retirement. Two chained phases: accumulation with monthly contributions, and month-by-month drawdown on the remaining balance, each with its own rate of return.
- Inflation. When you enter it, the real value is discounted from today, not from the retirement date.
What the calculations leave out
This matters as much as the above. None of the three calculators accounts for:
- Arrangement, valuation, appraisal or early-repayment fees.
- Insurance tied to a loan.
- Taxes, which depend on the country and the product.
- State pensions or other sources of income.
- Interest rates changing over time: the projection uses the rate you enter, held constant.
How the content is checked
The formulas are covered by automated tests that run on every change, including the edge cases that usually break tools like this — 0% rates, loans repaid ahead of schedule, capital that never runs out. The numeric examples in the guides are not illustrative: they are verified against what the calculator itself returns, so reproducing the example gives you the figure in the text. Guides are published in English and Spanish, the languages we can review; the interface is translated into ten.
Independence and how this is funded
There are no affiliate links, no sponsored comparison tables, no recommendations of specific products, and no personal data is sold or shared. The site will be supported by advertising, clearly marked and kept separate from the content; no advertiser has any say in what the guides say or how the tools calculate. If that ever changes, it will be stated here.
Errors and contact
If you find a calculation error, a bad translation or something that does not read clearly, telling us is the most useful contribution there is: it gets fixed and republished. A contact form is coming to the site; in the meantime, write to financialhelper@opportu.link.