POSTNET (Postal Numeric Encoding Technique) check digit for US Postal Service barcodes. Simple modulo-10 sum algorithm for ZIP codes and delivery point codes. Used in automated mail sorting from 1982-2013, superseded by Intelligent Mail Barcode.
| Property | Value |
|---|---|
| Category | Checksums |
| Sub-category | Postal Code |
| Security status | 🎓 Educational Only |
| Complexity | Beginner |
| Inventor | United States Postal Service |
| Year | 1982 |
| Origin | 🇺🇸 United States |
| Source | algorithms/checksum/postnet-checksum.js |
Status: 🎓 Educational Only
No vulnerabilities are recorded for this implementation.
3 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — ZIP code
| Field | Value |
|---|---|
input |
3132333435 |
expected |
05 |
Vector 2 — ZIP+4
Source: POSTNET validation
| Field | Value |
|---|---|
input |
313233343536373839 |
expected |
05 |
Vector 3 — ZIP+4+2
| Field | Value |
|---|---|
input |
3132333435363738393031 |
expected |
04 |