Report a calculation or source issue
Email thoopring@gmail.com. This mailbox is read by the operator, MinSoo Kim. There is no contact form.
When reporting an issue, include the page, the values you entered, the result you expected and the relevant product or measurement reference. Do not send payment information or other sensitive personal data.
What happens next
Confirmed calculation or source errors are corrected on the page and listed on the corrections page. Emails are kept only as long as needed to resolve the issue.