Royal Mail (RM4SCC)

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Royal Mail (RM4SCC)

The Royal Mail barcode — also called the Royal Mail 4-State Customer Code (RM4SCC) — was developed by the UK Postal System to automate mail sorting. The term “4-State” refers to the use of four different bar positions rather than widths to encode information. It can encode 5, 6, or 7 character postcodes along with a two-character Delivery Point Suffix (DPS) to ensure mail is properly sorted and reaches its intended destination. 

RM4SCC barcodes can encode numeric digits 0-9, all uppercase letters along with opening and closing parentheses. These codes must be a minimum of 35.98 millimetres wide and a maximum of 68.58 millimetres wide including all encoded data along with start and stop bars. This results in a density of between 20 and 24 bars for each 25.4 millimetres. Worth noting? All bars must be evenly spaced for this code to be properly read by handheld or automatic barcode scanners.


The Royal Mail barcode contains six key elements:

  • A Leading Quiet Zone
  • One Start Bar (Always Tracker, Ascender)
  • Symbol Characters that Represent Postcodes and DPS
  • A Check Digit
  • One Stop Bar (Always Tracker, Ascender, Descender)
  • A Trailing Quiet Zone

As noted above, the RM4SCC is a 4-state barcode, which means that each bar can be in one of four states, except for the start and stop bars which always follow the same pattern. The four states are:

  • Tracker (T) — Bars in this state occupy only the middle third of the barcode’s height.
  • Tracker, Descender (D) — Bars in this state occupy the bottom two-thirds of the barcode.
  • Tracker , Ascender (A) — Bars in this state occupy the top two-thirds of the barcode.
  • Tracker, Ascender, Descender (H) — Bars in this state occupy the entire height of the barcode.

By varying these states across the width of the barcode, it’s possible to encode numbers, capital letters, and parentheses. 

Positioning of these barcodes is also critical on Royal Mail packages and letters. The code must be no less than 18 mm and no more than 120 mm from the bottom edge. It must also be no less than 15 mm down from the top edge and no less than 15 mm from each side. Codes can be printed at any right angle — 0, 90, 180, and 270 degrees — and still be accurately read.

Common Use Cases

This barcode is used by the UK’s Royal Mail service to define both post codes and delivery point data. It was originally developed to automate the UK Postal Service’s mail system.

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