Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Computes a checksum only; does not verify an account, issuer, ownership or payment validity.
Example Calculation
- Payload digits without check digit: 7992739871
Payload digits without check digit = 7992739871. Primary result: 3.
Frequently asked questions
How do I use this calculator?
Enter payload digits without check digit. The result updates automatically. Use Reset to restore the example values.
What method does it use?
From the payload right, double alternate digits; subtract 9 above 9. Check digit=(10−sum mod 10) mod 10.. Computes a checksum only; does not verify an account, issuer, ownership or payment validity.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.