Contact

We are the CalcPrincipal team. Found an error in a calculator? Our method notes are written so you can name the exact line that is wrong — that is the most useful email we receive. Missing a calculator you expected to find? That is the second most useful.

Team email

[email protected]

We reply on working days. Tell us which calculator you used and what figures you entered, and we will re-run it ourselves before answering.