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We would love to hear from you. Email us at info@opalcalculator.com.

Report a mistake

If a result looks wrong, please tell us the calculator name, the values you entered and the result you expected. That lets us reproduce and fix the problem quickly.

Request a calculator

Describe what you want to work out, the inputs you have and the answer you need. Include an example with the correct result if you can.

Business and advertising

For partnerships or press enquiries, use the same address and put "Business" in the subject line. We usually reply within a few working days.