YouCalc exists to give clear, correct answers to everyday questions about money, math, health and the curious in-between. This page explains exactly how each calculator is built and kept accurate, so you can judge the results for yourself.
Formulas and sources
Every calculator is driven by an explicit, documented formula — never a black box. The math for each calculator lives in a single, isolated function that we test directly against known reference values.
Each calculator cites at least two independent, authoritative sources (for example, government agencies, standards bodies, peer-reviewed references, or official documentation). These sources are the basis for the worked examples we use to verify the calculator, and the most important ones are listed on the calculator’s own page under Sources.
How we test for accuracy
We build calculators test-first. Before a formula is written, we write automated tests that assert the calculator reproduces published reference values from the cited sources. A calculator does not ship until:
- Its math reproduces the cited reference values exactly,
- every input is validated and range-checked (we use schema validation to reject impossible or out-of-range entries before any calculation runs), and
- The full automated suite — unit tests, end-to-end browser tests, and automated accessibility checks — passes.
This suite runs again on every change, so a future edit cannot silently break a previously correct result.
Currencies and locales
Monetary calculators support multiple currencies rather than assuming US dollars; where relevant, the default is chosen from your region. Calculators are available in nine languages (English, Arabic, Urdu, French, Spanish, Portuguese, Russian, Indonesian, and Bengali), including full right-to-left support, and are tested against automated WCAG accessibility checks.
Review and updates
Each calculator records the date its content and formula were last reviewed. We revisit calculators when the underlying rates, rules, standards, or formulas they depend on change.
Beyond those triggered updates, every calculator is reviewed at least once every 6 months to confirm its method is still current, and its sources still hold. A review occurs immediately when a cited source publishes a material update, a tax band or rate is revised, or a user reports an issue or feedback that we can confirm.
Reviews are carried out and signed off by the YouCalc Team, which is responsible for accuracy across the site. You can read more about who we are and how we work on our Editorial policy page.
Limitations
Our calculators provide estimates for educational and informational purposes. They are not financial, medical, legal, or professional advice, and real-world figures can differ because of factors a general calculator cannot know. For consequential decisions, confirm the result with a qualified professional. See our Terms for the full disclaimer.
Corrections
If you believe a result is wrong, tell us. Every calculator page has a “Report issue or send feedback” button, or you can reach us through the Contact page. We investigate every report, and when we confirm an error, we fix it and update the calculator’s review date. Our full standards for accuracy and corrections are described in our Editorial policy.