Methodology & data sources

Last updated: 2 July 2026

This page explains how Gera Tools is made: how tools are built and verified, where reference data comes from, how results are computed, and how often everything is refreshed. Every data-backed page also shows its own source and "as of" date inline, so you can always see what a specific result is based on.

How tools are built and verified

Gera Tools is built by Gera Systems Ltd using AI-assisted software development: AI systems, working under human direction, implement the tools and draft the explanatory content. We say this plainly because we believe the honest answer to "can I trust an AI-built tool?" is to show the verification, not to pretend humans typed every line.

Before any page is published it must pass automated checks:

• It has to work. Every page is machine-verified to render without errors before it ships; pages that fail are pulled from the release, not published broken.
• It has to be well-formed. Each tool's metadata (title, description, category, structured data) is validated against a schema, and internal links and buttons are checked so they lead somewhere real.
• It has to show its working. Calculators display the formula or method used, on the page, so you can check the result yourself.
• Its data has to be traceable. Data-backed pages must cite a named primary source with an "as of" date. When a dataset cannot be verified against its claimed source, we discard it rather than publish it — we have done exactly that, and will again.

On top of the automated checks, humans decide what gets built, spot-check published tools, and investigate every correction report we receive. We don't claim a person has manually reviewed every one of our 10,000+ pages — that would be untrue — which is why the automated gates exist and why the corrections channel is a first-class part of the process, not an afterthought.

How results are computed

Calculators run entirely in your browser using transparent formulas — the same formulas we show on the page. We do not estimate or invent figures: a result is either computed from your inputs and published rates, or, where a required figure isn't reliably available, the tool says so rather than guessing. Worked examples are labelled as illustrative.

Primary data sources

We take reference figures from authoritative primary sources, including:

• UK government & statistics: GOV.UK, HM Revenue & Customs (HMRC), the Office for National Statistics (ONS), the Department for Work & Pensions (DWP), NHS Digital / NHS England, the Department for Education (DfE), DEFRA, the Land Registry, and the Bank of England — under the Open Government Licence v3.0.
• US federal sources (public domain): the Internal Revenue Service (IRS), the Bureau of Labor Statistics (BLS), the US Census Bureau, the Centers for Medicare & Medicaid Services (CMS), the Centers for Disease Control and Prevention (CDC), FEMA, and the FHFA.
• Industry & clinical reference: established datasets such as Bankrate / LodeStar for US housing and closing-cost averages, and EUCAST / CLSI for clinical microbiology reference. Clinical tools are reference aids only and are not a substitute for professional judgement.

Update cadence

Annual figures (such as tax bands, contribution limits and benefit rates) are updated when the relevant authority publishes the new tax or fiscal year. Periodic statistics (such as average costs, wages, and survey-based figures) are refreshed on their publication schedule. Each page carries the source and the "as of" date for its figures, so you can confirm currency at a glance.

Accuracy & corrections

We work hard to keep every figure correct and traceable to a named source, but errors are always possible. If you find a mistake in any tool, rate table or reference figure, please tell us via the Contact page — include the tool name or page link and what you expected — and we will investigate and correct it. Gera Tools is operated by Gera Systems Ltd (United Kingdom).

Tools and reference content are provided for general information. For decisions with financial, legal, medical or safety consequences, verify the result and seek appropriate professional advice — see our Disclaimer.