Privacy
You can use the calculators without an account. This page describes the data handled by the current site.
Calculations on your device
Calculation inputs are processed in your browser. Applied dimensions and units are kept in local storage so you can return to them. Reset replaces the saved values; clearing site data removes them. Shared links contain the selected dimensions in the URL, which may appear in browser history or hosting access logs.
Messages you send
A feedback submission stores your message, category, language, optional email and any calculation parameters you explicitly attach. These are accessible to the maintainer in a protected dashboard and are used to investigate or reply to your request. Do not include passwords or confidential project information.
Retention and deletion
Feedback is normally removed from the active database after 180 days. You can ask for earlier deletion through the contact form using your reference number. Operational backups, if enabled by the host, are managed separately.
Usage counts
The site counts public page views, calculation attempts, sharing and printing by day and page language. Counts are grouped by Beijing time (UTC+8). Page-view events contain only the page path, without query parameters or referrer URLs. They do not contain your dimensions, email or a persistent visitor identifier. Do Not Track and Global Privacy Control signals are respected. These are action counts, not unique visitors.
Security and hosting
Short-lived in-memory rate limits help reduce spam. The site does not store IP addresses in its feedback database. Hosting providers may maintain separate security or access logs. Administrator login uses an essential session cookie; public calculators do not require that cookie.