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
- Older mail and preprinted envelopes, such as reply envelopes printed before the change.
- Not on new mail. Since January 27, 2013, POSTNET barcodes haven’t qualified for automation prices, and the USPS removed them from its mail manual in 2018. The USPS still processes mail that carries one.
Anatomy
Every bar is the same width, and is either tall or short: A tall bar is a 1 and a short bar is a 0. Each digit is five bars, exactly two of them tall.
That gives three lengths:
Correction digit
The correction digit makes the sum of all the digits a multiple of 10. For ZIP Code 12345, the digits add up to 15, so the correction digit is 5.Variants and related types
- PLANET: the same idea with tall and short swapped, used for tracking.
- USPS Intelligent Mail: the 4-state barcode that replaced both.
Scanning it in your app
Specification
- USPS Domestic Mail Manual, 2017 archive, section 204: the POSTNET barcode standards before they were removed.
- POSTNET barcode discontinuation and removal: the 2013 and 2018 changes.