POSTNET vs PLANET vs Intelligent Mail Barcode – The Ultimate Postal Barcode Comparison

postnet vs planet vs intelligent mail barcode

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In this digital age, physical mail still holds a significant place in communication, especially in the business world. Therefore, the United States Postal Service (USPS) developed three postal barcode symbologies to improve the efficiency, accuracy and delivery and tracking capabilities of physical mail. 

  • Intelligent Mail barcode

Let’s take a closer look at each of these barcodes. 

What are POSTNET, PLANET and Intelligent Mail Barcodes? - A Quick Introduction

What is a POSTNET Barcode?

POSTNET, short for Postal Numeric Encoding Technique, is a postal barcode designed in the 1960s to help USPS sort, track, and identify mail. 

The POSTNET barcodes were designed to represent a five-digit ZIP code, a nine-digit ZIP+4 code, or an 11-digit delivery point barcode (DPBC). They were commonly used together with the USPS PLANET symbology. 

The term ZIP stands for Zone Improvement Plan. It is a numerical code that provides a specific zone for the address being mailed to. The United States is organised into ten different zones.  

In 1963, the USPS introduced 5-digit ZIP codes. 

The first digit of the 5-digit ZIP code represents one of the ten zones in the country. The following two digits indicate the regional centre or metropolitan area within that zone. The last two digits of the ZIP code represent the local post office or postal zone in larger cities.

In 1983, the postal service introduced the ZIP+4 code, which extended the size of ZIP codes to 9 digits. These additional digits provide details about the address within the local post office area.

The USPS created delivery point barcodes to provide a distinctive identification for all 115 million delivery points in the United States. As a result, more carriers could sort letter mail quickly before delivery by using DBPC. 

The number of bars in the POSTNET barcode varies based on its type. The 5-digit POSTNET barcode has 32 bars, the ZIP+4 POSTNET barcode has 52 bars, and the DBPC POSTNET barcode has 62 bars.

In 2009, the USPS replaced the PLANET barcode with a more capable Intelligent Mail barcode.

Check out our dedicated article on what is a POSTNET barcode to learn more.

What is a PLANET Barcode?

PLANET, short for Postal Alpha Numeric Encoding Technique, is another popular postal barcode technology developed to assist mailers in tracking letters and packages. It was introduced by USPS Confirm service, a service that allowed identifying and obtaining mainstream visibility for outgoing mail and incoming reply mail pieces. 

The PLANET code is made up of five vertical bars that can be either tall or short. It is worth noting that all PLANET codes begin and end with a tall bar. 

The PLANET barcode was replaced by the more sophisticated four-state Intelligent Mail barcode in 2013 as part of USPS’s efforts to improve mail tracking and providing enhanced tracking data capabilities.

Refer to our what is a PLANET barcode guide to learn more.

What is an Intelligent Mail Barcode?

The USPS Intelligent Mail barcode (IMB) is the newest and most advanced of the three postal barcode technologies. It combines the features of POSTNET and PLANET. The IMb effectively encodes data that carry a broad range of information, including enhanced tracking data, mail class and service type, and routing information. 

The Intelligent Mail barcode is made up of 65 vertical bars that represent four states: full bar, ascender, tracker, and descender. It encodes a string of 31 digits which includes a 20-digit tracking code and an 11-digit routing code. The Routing code contains a ZIP Code, ZIP+4 code or a delivery point code. 

IMB is a highly flexible barcode technology that offers significant benefits over POSTNET and PLANET.

Refer to our dedicated article on what are intelligent mail barcodes to learn more.

Similarities Between POSTNET, PLANET and Intelligent Mail Barcode

Four detailed resemblances of POSTNET, PLANET and Intelligent Mail Barcodes

Let’s take a look at the similarities between a POSTNET, PLANET and an Intelligent Mail barcode

  • PLANET, POSTNET and Intelligent Mail barcode are all USPS-developed symbologies used for automated mail sorting.
  • PLANET and POSTNET have been superseded by Intelligent Mail barcode as the primary USPS code system since 2009 and 2013, respectively.
  • All three codes can be used to track pieces of mail automatically from their origin to destination points within the United States Postal Service’s network of 115 million delivery points.
  • PLANET and POSTNET both encode data as a series of barcodes, while Intelligent Mail barcode combines these two code systems into one single symbol. 
  • The character set for PLANET, POSTNET, and Intelligent Mail barcodes includes only numeric digits from 0 to 9. 

POSTNET vs PLANET vs Intelligent Mail Barcode - What's the Difference?

Here are the key differences between POSTNET, PLANET and Intelligent Mail barcodes. 

Barcode Structure

Two points on barcode structure of POSTNET, PLANET and Intelligent Mail Barcodes

The PLANET, POSTNET, and Intelligent Mail barcodes use a combination of long and short black bars to represent data.

The PLANET and POSTNET barcodes are two-state symbologies that use short bars and long bars to represent each symbol character.

While PLANET and POSTNET barcodes may look similar at first glance, they have a significant difference. The digits of a PLANET code are inverted compared to those of a POSTNET code. This means that long bars in one correspond to short bars in the other, and vice versa.

Intelligent Mail Barcode is a four-state symbology that uses four different bar heights to represent each symbol character. 

Let’s take a closer look at the different components within the structures of PLANET, POSTNET, and Intelligent Mail barcodes. 

PLANET Barcode

The USPS used to offer a subscription service called Confirm that greatly improved mail tracking for mailers. The Confirm service comes in two types: Destination Confirm and Origin Confirm. 

Destination Confirm generates mail processing data for outgoing mail, while Origin Confirm generates data for the incoming reply mail. 

Users can choose to use one or both services. The PLANET code symbol element will differ based on the selected Confirm service.

There are eight key components in each Destination Confirm PLANET code. These include.

  • Leading Quiet Zone 
  • Tall Start Frame Bar 
  • Two-digit Service Type ID
  • Five-digit Subscriber ID assigned by USPS
  • Six-digit Mailer code
  • Check Digit
  • Tall Stop Frame Bar
  • Trailing Quiet Zone

The seven elements contained in the Origin Confirm PLANET codes are:

  • Leading Quiet Zone 
  • Start Bar
  • Two-digit Service Type ID 
  • Nine- or eleven-digit Customer ID
  • Check Digit
  • Tall Stop Bar
  • Trailing Quiet Zone


The components of the POSTNET barcode symbol are as follows.

  • Leading Quiet Zone
  • Start Bar (also known as a Frame Bar) 
  • Encoded address information (also referred to as Message Data)
  • Check Digit
  • Stop Bar (also known as a Frame Bar)
  • Trailing Quiet Zone

Intelligent Mail Barcode

The structure of the Intelligent Mail Barcode includes the following.

  • Leading Quiet Zone
  • Tracking Code component with 20 digits,
  • Routing Code component consisting of the delivery point ZIP Code.

The tracking code component contains the following symbol elements.

  • Leading Quiet zone
  • Barcode Identifier
  • Service Type Identifier
  • Mailer ID
  • Origin IMb tracing Customer Number
  • Mail processing equipment type and number
  • Date
  • Time
  • Serial Number (also called Sequence Number)
  • Trailing Quiet Zone

The routing code component of the Intelligent Mail barcode consists of the delivery point ZIP Code, which has 0, 5, 9, or 11 digits.

Data Capacity

List of three points on data capacities of POSTNET, PLANET and Intelligent Mail Barcodes

The data capacity of PLANET, POSTNET, and IMB codes is different. 

The Intelligent Mail barcodes have a fixed length of 65 bars. These 65 bars encode either 20, 25, 29, or 31 digits of information depending on the length of the zip code, which can be 0, 5, 9, or 11 digits long.

Comparatively, POSTNET barcodes can hold only 14 numeric characters, while PLANET barcodes contain 12 or 14 numeric characters depending on the length of the ZIP code. 

Barcode Density

Detailed points on barcode density of POSTNET, PLANET and Intelligent Mail Barcodes

The density of a barcode determines the number of characters that can be encoded in one inch.

The density of the PLANET and POSTNET barcodes is precisely 21 bars per inch. On the other hand, the Intelligent Mail barcodes have a density of 20 to 24 bars per inch.

Error Detection & Correction

Points about error detection and correction of POSTNET, PLANET and Intelligent Mail Barcodes

PLANET, POSTNET, and Intelligent Mail barcodes employ different techniques for error correction and error detection.

Error detection ensures the accuracy of barcode data and helps verify that the encoded data is correct. Barcode error detection is done by using a check digit. 

A check digit is a single digit added to the end of the barcode, which is computed based on the other digits present in a barcode.   

Error correction is a feature for preserving data integrity in symbols that encode large amounts of information. By encoding redundant information into the symbol, error correction allows scanners to detect and correct any missing or damaged data. Error correction provides a safeguard against accidental loss of valuable information.

The PLANET and POSTNET codes have a Modulo-10 check digit to detect errors but do not have error correction encoded.

The Intelligent Mail codes do not use check digits or error correction codes. Instead, they use a Cycle Redundancy Check (CRC) to confirm the correct barcode value. 

The Cycle Redundancy Check technique detects errors by comparing the encoded check value with the calculated check value using polynomial calculation. When the CRC check values do not match, it signifies a data error. Out of 130 bits of Intelligent Mail barcode, 27 are reserved for error detection. 


Two points on Availability of POSTNET, PLANET and Intelligent Mail Barcodes

PLANET and POSTNET barcodes are no longer in official use for mailing purposes but can still be used to administer internal operations. Both PLANET and POSTNET barcodes are free to generate, with numerous reliable websites providing access to free barcode generators.

On the other hand, the Intelligent Mail barcode is the official barcode system of the United States Postal Services. In order to use Intelligent Mail Barcodes, businesses must register with USPS and get their Intelligent Mail barcode.


Point of application of POSTNET, PLANET and Intelligent Mail Barcodes

The PLANET, POSTNET, and Intelligent Mail barcodes are postal barcodes developed to help automate mail sorting and tracking. However, they differ in their specific applications and capabilities.


PLANET codes help USPS track both incoming and outgoing mail by identifying the mailpiece’s origin and destination information. This allows for efficient mail tracking for customers and USPS. However, PLANET Codes do not contain detailed routing information.


POSTNET barcodes encode ZIP Code information to enable automated sorting of letter mail. They can represent a ZIP Code, ZIP+4 code or delivery point code to help route mail quickly to the correct destination. However, POSTNET barcodes do not provide tracking capabilities and only apply to letter-sized envelopes and flats.

Intelligent Mail Barcodes

The Intelligent Mail barcode combines the functions of PLANET and POSTNET codes and offers additional features. It encodes routing information for automated sorting and a unique ID to enable mail tracking. 

The Intelligent Mail barcode supports a range of mail sizes and types, replacing the specific-use PLANET and POSTNET codes with a single system offering more functionality.

Intelligent Mail Barcode vs POSTNET vs PLANET - Which is Better? and How to Choose?

When Should I Use a POSTNET Barcode?

The purpose of developing the POSTNET barcode was to encode ZIP Code information on letter mail for efficient sorting. Despite being discontinued for consumer mail in 2009, the POSTNET barcode can still be used for internal operations.

Advantages of using POSTNET barcodes.

  • The POSTNET barcode is a useful tool for organisations that need to sort large amounts of mailings quickly.
  • If an organisation needs to send out physical documents or packages on a regular basis to different branches, they can use the POSTNET barcode as part of their internal tracking system.

While the POSTNET barcode has limitations around the amount of information it can encode, it still remains useful for high-volume automated sorting.

When Should I Use a PLANET Barcode?

The PLANET barcode symbology was designed to identify and track postal items quickly. It was used in conjunction with the POSTNET barcode.

  • PLANET was a machine-readable standardised barcode system that allowed for fast and accurate sorting and routing.
  • PLANET barcode is compatible with existing USPS sorting equipment, making it easy to implement without significant infrastructure changes.
  • In the past, the Confirm services provided by the USPS, along with PLANET barcodes, gave mailers more transparency into the delivery status of their mailings. The confirm service allowed mailers to track outgoing and incoming mail.

When Should I Use an Intelligent Mail Barcode?

The Intelligent Mail barcode can encode more information in a smaller space on the mail piece. Mailers use the Intelligent Mail barcode to encode routing and tracking information on mail. 

The Intelligent Mail barcode can be read by automated mail processing equipment to sort the mail and provide tracking information to the mailers.

Here is a list of benefits of the Intelligent Mail barcode.

  • Compact barcode format with higher total data capacity compared to the other postal barcodes.
  • Grants mailers additional digits, enabling them to give a unique ID to s billion mail pieces per mailing. 
  • Provides more accurate and detailed information regarding mailings.
  • Makes better use of mail piece space by removing the necessity for using numerous barcodes.
  • Participate in multiple services programs by using one barcode.

Wrapping Up

In conclusion, postal barcodes are an essential tool in modern mail delivery and processing. Each of the PLANET, POSTNET, and Intelligent Mail barcodes has its own unique strengths and limitations. 

PLANET codes are great for tracking outgoing mail pieces but lack detailed routing information. 

POSTNET codes can encode ZIP Code information to enable automated sorting of letter mail but cannot provide tracking capabilities. 

The Intelligent Mail Barcode combines the functions of both PLANET and POSTNET codes with added features like a unique ID that helps track mail of multiple sizes and types.

We hope this article helped you understand the differences between Intelligent Mail bar code, POSTNET code and PLANET code. 

Thanks for reading! 

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