POSTNET (Postal Numeric Encoding Technique, Postal Numerical Codes) is a barcode used by the United States Postal Service. Code the postal code, postal code+4 yard, or delivery point number with half-height and full-height lines.
USPS Processing and Distribution Center in San Bernardino with POSTNET barcode on the exterior of the building
Each number is represented by five lines, two of which are long lines (ie, two-out-of-five code). The long line is the 1 in the Binary code. Each line, from left to right, represents the values 7, 4, 2, 1, and 0 (although the number 0 is encoded as 11000, not 00001). The start and end symbols are long lines (often called “guardrails” or “frames,” represented by the letter “S” in USPS TrueType fonts), appended to the right of the postal code, postal code+4, and drop-off point number Check code.
The encoding method of POSTNET
| Numbers | Digits | Barcode | ||||
|---|---|---|---|---|---|---|
| 7 | 4 | 2 | 1 | 0 | ||
| 0 | 1 | 1 | 0 | 0 | 0 |  |
| 1 | 0 | 0 | 0 | 1 | 1 |  |
| 2 | 0 | 0 | 1 | 0 | 1 |  |
| 3 | 0 | 0 | 1 | 1 | 0 |  |
| 4 | 0 | 1 | 0 | 0 | 1 |  |
| 5 | 0 | 1 | 0 | 1 | 0 |  |
| 6 | 0 | 1 | 1 | 0 | 0 |  |
| 7 | 1 | 0 | 0 | 0 | 1 |  |
| 8 | 1 | 0 | 0 | 1 | 0 |  |
| 9 | 1 | 0 | 1 | 0 | 0 |  |
| Start/End | – | – | – | – | 1 |  |
Check code algorithm
The checksum plus other numbers in the barcode will be a multiple of 10. That is, the sum of the barcode contents is divisible by 10.
The steps to calculate the checksum are as follows:
- Add all numbers together. For example, the sum of the zip code + 4 codes 55555-1237 is 38.
- Find the remainder when the number is divided by 10. In this case 38÷10=3…8.
- Subtract the result of the previous step from 10. In this case 10-8=2.
If the calculation is correct, the sum of the barcode contents will be a multiple of 10. Continuing the example above, (5+5+5+5+5+15+2+3+7+2)=40, and 40 mod 10=0.
Example
The check digit of the postal code+4 code 55555-1237 is 2, and the complete barcode content is 5555512372. Adding start and stop symbols will show as:
Postnet的条码格式
There are four formats of Postnet barcodes used by the U.S. Postal Service
| name | number of digits | Number of bus bars | content | Remark | ||
|---|---|---|---|---|---|---|
| ZIP | +4 | |||||
| A code | 5 | 32 |  |  | | |
| B code | 6 | 37 | last two | | | In the early days of postal automatic mail processing, it was used when OCR was used to identify A Code, and it is no longer used. |
| C code | 9 | 53 | | | | Messages can be segmented into carts |
| DPBC (Delivery Point Bar Code) | 11 | 62 | | | | The Post Office can easily sequence the delivery due to the inclusion of the delivery point number |
In the fall of 2009, POSTNET was approved by Smart Post Barcode (English: Intelligent Mail barcode) replaced. Originally expected to begin full use of smart postal barcodes in May 2011, the USPS postponed the date to January 28, 2013.
