Decode one
Scan or paste a barcode and see every part of it.
Make one
Generate a valid barcode from fields.
Where you’ll see it
- Letters and flats in the US mail, usually above or below the address.
- Business reply mail, printed on the reply card or envelope.
Anatomy
Each of the 65 bars is in one of four states: The bars encode up to 31 digits in two parts:
The first four parts form the 20-digit tracking code.
No direct mapping from digits to bars
Unlike POSTNET, the bars don’t stand for individual digits. An encoder converts all 31 digits together into the 65 bars, so you can’t read or write an Intelligent Mail barcode by hand. The USPS publishes the encoder, and printing it needs a special font.Error detection
The encoding includes its own error detection, so the routing code doesn’t need the correction digit that POSTNET used. Scanners verify it and report only the digits.Variants and related types
- POSTNET and PLANET: the barcodes it replaced.
- Intelligent Mail package barcode (IMpb): on parcels. Despite the name, it’s a GS1-128, not a 4-state barcode.
- Royal Mail 4-State and Australia Post 4-State: 4-state barcodes from other postal services that look similar but encode differently.
Gotchas
- 31 digits, or fewer. The routing code can be empty, 5, 9 or 11 digits, so a valid scan can be 20, 25, 29 or 31 digits long.
- The serial number isn’t unique forever. Mailers can reuse serial numbers after a period the USPS defines. Pair it with the mailing date if you store it.
Scanning it in your app
Specification
- USPS Intelligent Mail barcode: an overview, the encoder, and the USPS-B-3200 specification.
- POSTNET barcode discontinuation: the 2013 change that made it required.