Japan / Individual Number
My Number Validator (Japan)
Check whether a Japanese Individual Number (My Number, マイナンバー) is well formed: 12 digits and a valid check digit. Full-width digits are accepted.
My Number Validator (Japan): The first 11 digits are multiplied by 6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 and added. The check digit is 11 minus the remainder after dividing by 11, or 0 when the remainder is 0 or 1. Unlike many ID numbers, a My Number holds no birth date, sex, or place. Results agreed with the python-stdnum library on 6,000 numbers. Runs 100% locally in your browser with zero server file uploads.
- Category
- Business & admin tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
The 12th digit is a check digit: the first 11 are multiplied by 6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 and added, and the digit is 11 minus the remainder after dividing by 11, or 0 when that remainder is 0 or 1. The number contains no personal details. Only the format is checked; nothing leaves your browser.
A worked example
For 12345678901, the digits times 6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 add up to 212. 212 divided by 11 leaves 3, and 11 − 3 = 8, so the full number is 1234 5678 9018.
To turn full-width digits copied from a form into half-width ones, use the full-width and half-width converter.
What the check digit catches
Nearly every single mistyped digit is caught. Because remainders of 0 and 1 both give the check digit 0, a slip that moves the remainder between them is missed, and so are some swaps of two neighbouring digits.
How to use it
- Type or paste 12-digit numbers, one per line, with or without spaces or hyphens.
- Read which are valid.
- For one that fails, see the check digit it should have.
Privacy & limitations
Numbers are checked in your browser and never sent anywhere. Japanese law limits collecting and storing My Numbers to purposes such as tax and social security, so check only numbers you are allowed to handle.
Related tools
Frequently asked questions
Does a valid result mean the number was issued?
No: only that it is correctly formed, which catches most typing mistakes.
Is the Corporate Number checked the same way?
No: the 13-digit Corporate Number (法人番号) puts its check digit first and uses a different calculation.
Can I type full-width digits?
Yes. Full-width digits, spaces, and hyphens are converted before the check.
Free tool · runs in your browser · no account required