International · Validation
Japan My Number check digit validator.
マイナンバー（個人番号）チェックデジット検証
Check that a 12-digit My Number (個人番号) has the right check digit in its last position. Format and checksum only. Everything runs in your browser.
How it works: the first 11 digits are multiplied by fixed weights, summed, and reduced mod 11 to give the 12th digit (検査用数字). A remainder of 0 or 1 gives a check digit of 0.
Inputs
Result
Enter a My Number and press Check.
How the My Number check digit works
マイナンバー チェックデジットの計算方法
A My Number (個人番号, マイナンバー) has 12 digits. The last digit is a check digit (検査用数字) calculated from the first 11. The calculation is public: the number itself encodes no personal information.
| Step | What happens |
|---|---|
| 1 | Number the first 11 digits P11 (leftmost) down to P1 (rightmost of the 11) |
| 2 | Weight Qn = n + 1 for n from 1 to 6, and n − 5 for n from 7 to 11. Left to right the weights are 6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 |
| 3 | Add the products Pn × Qn, then take the remainder mod 11 |
| 4 | Check digit = 11 − remainder, or 0 if the remainder is 0 or 1 |
Example: the first 11 digits 62149832025 give a weighted sum of 180, a remainder of 4, and a check digit of 11 − 4 = 7, so 6214 9832 0257 (the published python-stdnum example) passes.
Checksum only, not an identity lookup
A passing result means only that the 12 digits are internally consistent. It cannot confirm that the number was ever issued, is currently in use, or belongs to anyone. Only Japanese authorities can do that.
Sources
Weights and formula: python-stdnum, stdnum/jp/in_.py, with the same method described on Japanese Wikipedia (個人番号), which cites 平成26年総務省令第85号 (Ministry of Internal Affairs and Communications ordinance No. 85 of 2014) article 5.
Checksum only — not an identity lookup
This tool checks the 12-digit format and mod 11 check digit entirely in your browser. It cannot confirm a number was issued or belongs to anyone, and it does not query any government system. Nothing you type is transmitted, stored, or logged.