How to use
Run a clean first pass
- Enter a 10-digit ID number, or load a sample number.
- Click validate to see the pass/fail badge and decoded summary.
- Read the checksum ladder to understand how each step affects the final result.
Input
Enter a 10-character ID (1 letter + 9 digits).
Enter an ID number, then validate.
Result
Format and checksum verification.
Waiting to validate
--
Enter a Taiwan national ID number.
VALIDIssuing region
--
Checksum ladder
| Pos | Digit | Wt | Prod | Sum |
|---|
Total: --
|
Remainder: --
How it works
This tool validates Taiwan national ID numbers locally in your browser. No data is sent to any server. The first letter maps to an issuing region, and the remaining 9 digits are verified through a weighted checksum.
Common uses: testing form validation rules during development, understanding the weighted checksum algorithm, and teaching the step-by-step calculation process.
Note: This tool only verifies format correctness. It cannot confirm whether an ID actually exists. Results are for reference only.
Quick guide
Use cases, answers, and nearby tools
Compact below-tool notes that help first-run users and repeated visitors move faster without changing the main interface.
Chinese search: 身分證 驗證、身分證 檢查碼、身分證號碼 格式、身分證字號規則、身分證英文代碼、台灣 ID 驗證
Examples
Real jobs this page helps with
- Format and checksum validationEnter an ID number to confirm whether the region code, gender code, and checksum are all correct.
- Front-end form validation referenceWhen building signup, membership, or payment forms, mirror the checksum logic to reject mistyped IDs before submitting.
- Educational referenceUse the checksum ladder to explain the structure and validation logic of Taiwan ID numbers.
FAQ
What people usually want to know
What does the letter in a Taiwan ID mean?
The first letter encodes the city/county of first household registration — e.g. A Taipei, B Taichung, C Keelung, D Tainan, E Kaohsiung, F New Taipei. It marks where the ID was registered, not where the person lives now.
What does the first digit mean?
The first digit after the letter (the 2nd character) is the gender code: 1 for male, 2 for female.
How is the checksum calculated?
The leading letter is mapped to a two-digit code, then it and the following digits are multiplied by fixed weights and summed; the final digit makes the total satisfy the divisibility rule. The tool shows this checksum ladder step by step.
Does passing mean the ID exists?
No. Passing only means the format and checksum are mathematically correct — not that the number exists in government records or belongs to anyone.
Is my ID number uploaded?
No. All validation runs locally in your browser; nothing is sent or stored.