POSTNET
The US Postal Service's retired height-encoded delivery-point barcode: tall and short bars representing ZIP + delivery point + check digit.
POSTNET Specification
| Character set | Digits 0-9 |
| Data length | 5, 6, 9, or 11 digits + 1 check digit |
| Check digit | Mod 10 check digit, mandatory |
| Density | Fixed — one digit per five bars regardless of data |
| Module width (X-dimension) | Bars 0.02-0.025 inch wide; height encodes the data |
| Print ratio | Two heights: full and half (heights are the data) |
| Magnification | USPS fixed dimensions (bar height and pitch specified) |
| Quiet zone | 0.125 inch right of the symbol (framing rule) |
| Standard | US Postal Service (retired 2013 in favor of IMb) |
| Origin | US Postal Service, 1982 |
Not generated by barcodegen.net
POSTNET is documented here for completeness, but our free generator does not produce this symbology. The closest supported format is Code 128.
What Is POSTNET?
POSTNET (Postal Numeric Encoding Technique) encoded data in bar heights rather than widths: each digit maps to a pattern of five bars, of which exactly two or three are tall. The classic USPS format carries an 11-digit delivery point ZIP or 9-digit ZIP+4, closed by a Mod 10 check digit, printed across the bottom of envelopes for delivery-point sorting.
USPS retired POSTNET in favor of Intelligent Mail (OneCode) in 2013, requiring mailers to migrate; POSTNET symbols remained readable during transition but bulk-mail discounts now require the IMb. POSTNET is included here as reference because legacy mail archives and older presort documentation still reference it. Any new US mail barcode is Intelligent Mail.
Common Applications
- USPS delivery-point sorting (retired)
- Legacy presort mail archives
Related Barcode Types
USPS's retired tracking barcode for inbound confirmations — the inverse-height sibling of POSTNET.
The UK's 4-state postal barcode: bars in four height-tracker combinations, sorting mail with a compact machine-readable postcode line.
Deutsche Post's 12-digit parcel identification barcode, encoded in Interleaved 2 of 5 with Mod 10 check digit.