support@calchandbook.com — we usually reply within one business day.
What to include
- Bug or wrong result: the calculator name, your inputs and units, and what you expected. A screenshot or the PDF report helps.
- Billing: the e-mail used at checkout and your Paddle order number.
- Calculator request: the case you need and the reference you use for it (textbook, code clause or design aid).
Operator
CalcHandbook is operated by MARFEN-MAHMUT TARI, sole proprietor, Türkiye. See the Terms of Service, Privacy Policy and Refund Policy.