Editorial Policy & Methodology

People use ToolKnack to make real decisions about money, travel, study and health. This page explains how we build our tools, where our numbers come from, how we check them and how we keep them current.

How our calculators work

• We use standard, published formulas: the amortization formula for loans and mortgages, compound growth for savings, the Mifflin-St Jeor equation for calories and WHO/CDC ranges for BMI.
• Tax calculations use official figures, such as the IRS 2026 tax brackets and standard deductions and the Social Security wage base announced by the SSA.
• Every tool page explains its method and shows a breakdown, so you can check the result yourself.
• Before publishing, we test each calculator against hand-calculated examples; the worked examples on our pages are computed with the same code that powers the tools.

Where our data comes from

• Visa requirements: the open Passport Index dataset, refreshed regularly; each page shows its last update date.
• Citizenship and study guides: compiled from official government sources (immigration ministries, embassies and official study portals). Each guide links to its source and shows a review date, and we note recent law changes.
• Emission factors: the UK Government's greenhouse gas conversion factors (DESNZ/DEFRA), used by companies for carbon reporting, plus published research for digital emissions.
• Exchange rates and metal prices: European Central Bank reference rates and live gold and silver spot prices.
• Phone specifications: manufacturers' published specifications and US list prices.

Review and updates

• Rules that change often (tax figures, visa and citizenship rules, student visa conditions) are reviewed at least every quarter and whenever a major change is announced.
• Each tool page shows when it was last updated; guides show their review date.
• We verify important facts against at least one official or primary source before publishing.

Limitations

Our tools give estimates for planning and education. They are not financial, tax, legal, immigration, medical or religious advice. For important decisions, confirm with a qualified professional, the relevant authority or a scholar you trust.

Advertising and independence

ToolKnack is free because it shows ads. Advertisers have no influence over our tools, calculations or recommendations. Ads are clearly separated from content and never placed where they could be mistaken for buttons. If a page contains affiliate links (for example "Check price" on the phone finder), they are marked as sponsored and never change how products are ranked.

Privacy by design

Most tools run entirely in your browser: the numbers, files and text you enter are not uploaded or stored. See our Privacy Policy for details.

Corrections

If you spot an error or an outdated rule, please tell us via the contact page or the feedback box on any tool. We review every report and correct confirmed errors promptly.