General support
Use the email address shown on this page for broken links, usability feedback, accessibility issues, and questions about the site.
Report a calculation or content error
Include the exact tool URL, the values you entered, the result you received, the result you expected, and a reliable source where applicable. Do not attach confidential source files.
Privacy requests
Use the subject line Privacy Request and describe the request and the country or region relevant to it. Because the site has no accounts, we may need enough information to locate a specific server log or prior email, but we will not ask for unnecessary identity documents.
Response expectations
We aim to review legitimate reports promptly, but this free service does not promise immediate or round-the-clock support. Security reports and material calculation errors receive priority.