About Contania
Contania is a Brazilian site of free online calculators with one simple commitment: never hand you a number without showing the math behind it.
What Contania is
Over 200 calculators across 12 categories — taxes, work, finance, health, dates, education, construction and more — in Portuguese and English, free and with no sign-up. Every page ships the tool together with the formula used, a step-by-step breakdown, worked examples, FAQs and the sources behind the numbers.
Why it exists
Most calculator sites return a number and hide the path to it. That works until the number really matters — a payroll deduction, a fine, a final grade, a mortgage. If you can't see the math, you can't check it, challenge it or learn from it. Contania exists to invert that: the right answer, explained step by step.
How the content is made
Each calculator starts from primary sources — legislation, official tables, technical standards or reference literature, always cited on the page itself. The formula is implemented in code and verified by automated tests against independently computed cases, including edge cases. The explanatory content is written for the real questions people bring to the page. The full process is described in our Methodology.
Who maintains it
Contania is an independent editorial project made in Brazil. It is not owned by any bank, broker or consultancy, and it is never paid to recommend a product, service or decision. The operation is funded by clearly labeled advertising, which has no influence over content or results. We speak institutionally as Contania; the direct channel to the team is contato@contania.app.
Transparency and limits
The calculators are informational and educational: estimates to help you understand and check a computation, not professional advice. On sensitive topics — health, finance, taxes, law — pages carry explicit notices and the recommendation to confirm with a qualified professional. The values you type are processed in your browser and are not stored by us.
Found an error?
A reported error is the most valuable feedback a calculator site can get. If a result looks wrong, write to contato@contania.app with the page link and the values you used — we investigate, fix and update the page's revision date. Details are on the Contact page.