Contact
We read every email and reply within two business days.
General
Corrections
Found an error in a calculator? Email us with the URL and a brief description. We log every correction in our public changelog.
Tool requests
Need a calculator we don't have? Tell us what input you'd give and what answer you'd want. If it's broadly useful, we'll build it.
Press & partnerships
For media inquiries, embed partnerships, or API access, email calc@3stf.com with "Partnership" in the subject line.