Difference Between UCS 2 and UTF 16

UCS-2 and UTF-16 are two variants of character encoding, one being new and the other being old. These are the methods that employ two bytes (eight bits) to encode each letter, thus the extensions 2 and 16.


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These are different encoding standards in which letters are rendered by a remedied bit string, such as 16 bits (2 bytes). Most communications systems utilize it as a backup during core activity regarding message generation.

And this article can assist you to specify their use as well as the distinctions between various encoding codes.

UCS 2 vs UTF 16

The difference between UCS 2 and UTF 16 is that UCS-2 is an outdated system that has already been deprecated in favor of the considerably modern and more sophisticated UTF-16. UCS-2 is a constant width compression that utilizes two bytes for every character, allowing it to encode up to 216 letters, or little more than 65 thousand characters of various types. UTF-16, but on the other hand, is a flexible width embedding system that requires a minimum of two bytes and a max of four bytes for each letter.

UCS 2 vs UTF 16

UCS-2; ‘Universal Character Coded Set’, is a letter coding system whereby each character is encoded by a resolved 16-bit string (2 bytes).

Most GSM networks utilize it as a backup when communication cannot be coded utilizing GSM-7 or if a dialect needs more than 128 bits to be shown.

UTF-16 simply stands for ’16-bit Unicode Transformation Format’ is a text encoder that can encode all 1,112,064 valid Ascii encoding units just like the UCS 2.

Because code units are encrypted using one or two 16-bit code subunits, the coding is flexible in duration.

Comparison Table

Parameters of ComparisonUCS 2UTF 16
Full FormUCS-2 is an abbreviation for Unicode Character Set Coded in 2 Octets.Unicode Transformation Format-16 often abbreviated as UTF 16.
DefinitionUCS-2 is a Unicode character encoding with a constant width of two bytes.UTF-16 is a variable-width character set that requires two or four bytes for each letter.
PointsOnly 65,536 code points can be encoded.1,112,064 code points can be encoded in UTF 12.
ApplicationWindows versions prior to Windows NT 3.1 through Windows 95.From Windows 2000 to current versions and JAVA based applications as well.
CompatibilityNot backwardly compatible and is obsoleteBackward compatibility is available and is not obsolete.

What is UCS 2?

UCS-2 is an abbreviation for Unicode Character Set Coded in 2 Octets. The International Organization for Standardization (ISO) defines UCS-2 as well as the other UCS specifications in ISO 10646.

UCS-2 allows for a total of 65,536 letters, or hex values ranging between 0000h to FFFFh (2 bytes). UCS-2 glyphs are synced with Unicode’s Basic Base Plane.

Because far more than 128 symbols are regularly employed in multiple languages, a bigger array of possible characters is required. UCS-2 has been deployed in many GSM data networks and is widely regarded as a de-facto backup.

According to the Unicode standard, UCS-2 is an outdated encoding since it was not meant to support characters in Unicode such as extra or ‘astral’ planes.

Plane 0, the Fundamental Multilingual Plane, offers character compression algorithms for the glyphs that are thought to be the most regularly used in languages. UCS-2 has a coding point limit of FFFFh, totaling 65,536 potential characters.

UTF-16 is the heir to UCS-2, and it can handle Base plus 16 Supplemental planes, for a total of 10FFFFh characters, or 1,114,112 coding points. Now since the term “character” is overused, it is far more accurate to allude to code points.

Coding points are the fundamental unit of storing information in coding and enable separation from letter terms.

What is UTF 16?

UTF-16 (16-bit Unicode Transform Format) is a glyph encoding (similar to UCS 2) that can encode all 1,112,064 quasi Ascii code points. Because code points are encoded using one or two 16-bit coding subunits, the coding is flexible in length.

Until it became evident that far more than 216 (65,536) coding units were required, UTF-16 evolved from an older set of 16-bit coding known as UCS-2 (for 2-byte Universal Character Set).

Fundamentally, systems like Windows by Microsoft, the Core java language, and Typescript employ UTF-16. On Microsoft Windows, this is also commonly used for clear text or word-processing file systems.

On Unix-like platforms, it is seldom used for directories. As of May 2019, Microsoft appears to have modified its position and now supports and advises the use of UTF-8.

UTF-16 seems to be the only web-encoding that is inconsistent with ASCII, and that has never gained much traction on the internet, where it is utilized by less than 0.002 % (a little more than one-thousandth of one cent) of online sites.

In contrast, UTF-8 is utilized by 98 percent of all online pages.

The Web Hyperlink Application Technology Working Group considers UTF-8 to be “the required format for all [text]” and believes that web apps should not utilize UTF-16 for security concerns.

Main Differences Between UCS 2 and UTF 16

  1. UCS 2 is the short form of the phrase, ‘Unicode Character Set Coded in 2 Octets’ whereas UTF 16 stands for ‘Unicode Transformation Format-16’.
  2. The UCS-2 encoding method is constant width, whereas the UTF-16 encoding scheme is flexible width.
  3. UCS 2 is now considered obsolete whereas UTF 16 is the latest encoding scheme compatible with most web pages and networks.
  4. The UCS 2 does not allow normalization whereas the UTF 16 allows normalization.
  5. The UCS 2 is not backward compatible whereas the UTF 16 is backward compatible. 


  1. https://www.twilio.com/docs/glossary/what-is-ucs-2-character-encoding
  2. https://www.oreilly.com/library/view/xml-in-a/0596007647/ch05s05s01.html
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