How we check compatibility and build calculators
This page sets out how every guide on Nordprix is put together. If a page breaks one of these rules, that's a mistake, and we'd like to hear about it.
Sources we use
- Standards and specifications from the bodies that publish them, such as the USB Implementers Forum.
- Manufacturers' own documents: specification sheets, manuals and support pages.
- Government data and calendars, such as the US Energy Information Administration for electricity prices, the Office of Personnel Management for federal holidays and the Consumer Product Safety Commission for safety guidance.
- Retailers' own announcements for sale events, from their websites or press pages.
Seller listings, forum posts and other review or shopping sites can point us to a question. They are never the source of an answer.
Each source is linked where we use it, with the date we read it. Quotes are copied exactly. For long documents, we name the section.
Compatibility checks
- We answer only from what a standard or a manufacturer has published. If the document that would settle the question doesn't exist or isn't public, the page says so.
- We name the version, rating or model number the answer depends on, so you can check it on your own product.
- We check against manufacturer and standards documentation. We don't run lab tests or hands-on reviews, and pages don't suggest otherwise.
- Safety points come from the manufacturer or a safety authority, never from our own judgment.
Calculators
- The formula is printed on the page as plain arithmetic.
- Every assumption has a stated default, and you can change it.
- Data from outside, such as an electricity price, names the publisher, the table and the month it describes. Averages are labeled as averages.
- Results are rounded only at the end; money is shown to the cent.
- The calculation runs in your browser. Nothing you enter is sent to us.
- Each calculator page includes a worked table you can read without JavaScript.
Comparisons
- Products are compared on figures their makers publish, converted to the same units.
- Where two makers measure something differently, we say so rather than set the numbers side by side as if they were the same.
- We don't invent overall scores or star ratings, and we don't print retail prices: they change too often, so the retailer's page is the place to check.
Sale dates
- A date goes in the calendar only if it is fixed by law or the federal holiday calendar, or if the retailer has announced it.
- Events that haven't been announced are listed as “not yet announced”, never as last year's date moved forward.
- We don't publish discount codes.
Data sources currently in use
- Electricity prices: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A (residential, monthly).
- Federal holidays: U.S. Office of Personnel Management.
- USB charging and cable ratings: USB Implementers Forum documents and the USB Type-C specification.
- Efficiency rules and test methods: the Department of Energy's standards and test procedures (10 CFR Part 430) and the Federal Trade Commission's EnergyGuide labeling rule (16 CFR Part 305), as published in the Electronic Code of Federal Regulations; ENERGY STAR program requirements.
- Electric vehicle efficiency: EPA ratings published at fueleconomy.gov.
- HDMI cables: HDMI Licensing Administrator's cable and certification pages.
- Product specifications: each manufacturer's own pages, linked on the page that uses them.
Dates and updates
Every page shows a “Last updated” date: the last time it was checked against its sources. Pages built on regularly published data say which release they use and are updated when the publisher releases newer figures. We aim to re-check every page against its sources at least every 90 days. Each guide ends with a short record of what changed and when.
Corrections
Email contact@nordprix.com with the page address, what's wrong and the source that shows it, ideally with “Correction” in the subject line. We check the claim against the source. If the page was wrong, we correct it and add a dated note to the record at the bottom of the page.
Affiliate links
Commissions never decide what a page says. The rules are on the affiliate disclosure page.
Who's behind Nordprix
Nordprix is an independent site run by Halil Erdoğan, a former news editor. See About.