Define the method
Record the formula, units, assumptions, decision rules and expected outputs before judging the interface.
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Trust & Transparency
Editorial & Calculation Methodology
This page explains where Yootils’s formulas and factual claims come from, how calculations are checked, and what happens when a source or rule changes.
Our Publishing Principles
Yootils tools should be useful, understandable and honest about their limits. A precise-looking result is not necessarily an exact real-world answer, so each supported tool page identifies its method, assumptions, primary sources and the checks applied to it.
We do not describe content as “expert reviewed”, “medically approved” or “verified” unless that specific review has actually taken place and the reviewer can be identified.
The checks that enforce this are automated and listed in full: see How We Test for what runs on every change, what each check catches, and what none of them can prove.
How A Tool Is Researched & Checked
Select sources
Prefer the organisation responsible for the standard, rule or dataset and original research for published equations.
Test the calculation
Check worked examples, boundary values, unit conversion, rounding and reverse calculations where applicable.
Publish limitations
State what the result leaves out, where estimates can vary and when professional advice may be appropriate.
Source Selection
Sources are chosen because they directly support a visible formula, threshold, definition, dataset or limitation—not simply because the publisher is well known.
Preferred Source Order
- Standards bodies and dataset maintainers, such as BIPM, ISO and IANA.
- Government departments, regulators and public health bodies, such as HMRC, the WHO and the NHS.
- Original peer-reviewed research, normally linked through PubMed.
- Established educational references when no primary standard or original publication is appropriate.
Review Frequency
The visible “Sources reviewed” date records when the cited source links and their use on the page were last checked. It is not a claim that the source itself was newly published on that date.
| Content | Review Trigger |
|---|---|
| Tax rates, allowances and government schemes | Each tax year and after relevant official announcements |
| Time zones, DST and bank holidays | After dataset releases, rule changes and annual holiday updates |
| Health guidance | At least annually and when the cited authority updates its guidance |
| Fixed mathematical standards and formulas | When the standard changes or a material implementation issue is found |
| Word-game lexicons | When the named lexicon version changes |
Use of AI
AI may assist with research organisation, drafting, code review and test-case generation. It is not treated as a factual source. Published evidence links must resolve to the named external source, and generated calculator changes must still pass code and visual checks.
Independence & Limitations
Sources do not pay to be cited. A link is included because it supports the page. Calculators provide informational estimates and do not replace financial, medical, legal or other professional advice. Important decisions should be checked independently using current information that applies to your circumstances.
Corrections
If you find an incorrect formula, stale rule, broken citation or unclear limitation, please send the page address and details through the contact page. Material errors are corrected in the calculation and explanatory copy; the source review date is updated only after the page has been checked again. Corrections that change a result are announced on What’s New rather than applied quietly, so anyone who used the old figure can see that it moved.