Intelligent Mail Barcode

Intelligent Mail barcode (sometimes abbreviated as USPS4CB or 4CB) is a 65-bar code for use on mail in the United States. The term “Intelligent Mail” refers to services offered by the Postal Service for domestic mail delivery. (IM®) is intended to provide greater information and functionality than its predecessors like POSTNET. Intelligent Mail® barcode has also been referred to as One Code Solution and 4-State Customer Barcode abbreviated 4CB ,4-CB or USPS4CB. The complete specification can be found in USPS Document USPS-B-3200E. It effectively incorporates the routing ZIP code and tracking information included in previously used postal barcode standards.

This applet converts user input into Intelligent Mail Barcode or shows red crossing lines if this is not possible.

The Intelligent Mail initiative announced by the US Postal Service in 2003 will be required starting in fall of 2009 for mailers to receive the maximum USPS automation discounts. Some of the benefits include improved deliver-ability, new services and increased overall efficiency.

The Intelligent Mail data payload

The Intelligent Mail barcode is a height-modulated barcode that encodes up to 31 decimal digits of mail-piece data into 65 vertical bars.

The code is made up of four distinct symbols, which is why this barcode was once referred to as the 4-State Customer Barcode. Each bar contains the central "tracker" portion, and may contain an ascender, descender, neither, or both (a "full bar"). In total, the new barcode will carry a data payload of 31 digits representing the following elements:

Barcode identifier

A two-digit value that indicates the degree of pre-sorting this mail piece received before being presented for mail delivery.

Service type identifier

Intelligent Mail barcode components
Index of first digit Length Name
1 2 Barcode identifier
3 3 Service type identifier
6 6 or 9 Mailer ID
12 or 15 9 or 6 Sequence number
21 11 Delivery point ZIP code
A three-digit value representing both the class of the mail (such as first-class, standard mail, or periodical), and any services requested by the sender.

Mailer ID

A six or nine-digit number assigned by the USPS that identifies the specific business sending the mailing. Higher volume mailers are eligible to receive six-digit Mailer IDs, which have a larger range of sequence numbers associated with them; lower volume mailers will receive nine-digit Mailer IDs. To make it possible to distinguish six-digit IDs from nine-digit IDs, all six-digit IDs begin with a digit between 0 and 8, inclusive, while all nine-digit IDs begin with the digit 9.

Sequence number

A mailer-assigned six or nine-digit ID specific to this piece of mail, which the mailer must ensure is unique for a 45-day period after it is sent. The Sequence Number is either six or nine digits, based on the length of the Mailer ID. If the Mailer ID is six digits long, then the Sequence Number is nine digits long, and vice versa, so that there will always be fifteen digits in total when the Mailer ID and the Sequence Number are combined.

Delivery point ZIP code

This section may be omitted, but if it is present, the five, nine, or eleven-digit forms of the ZIP code are also encoded in the Intelligent Mail barcode. The full eleven-digit form includes the standard five-digit ZIP code, the ZIP + 4 code, and a two-digit code indicating the exact delivery point. This is the same information that was encoded in the POSTNET barcode, which the Intelligent Mail barcode is intended to replace. [1]


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  1. 1  Intelligent Mail Barcode Specification