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UTF-8 vs. UTF-16: What’s the Difference?

In today’s fast-paced digital world, the importance of encoding languages and characters cannot be overstated. As you navigate through websites or create content online, you may have come across terms like UTF-8 and UTF-16.

UTF-8 and UTF-16 are both character encoding schemes used to represent Unicode characters. UTF-8 uses 8-bit code units to represent characters, while UTF-16 uses 16-bit code units. UTF-8 is more compact and widely used on the web, while UTF-16 is commonly used in Windows systems and some programming languages.

UTF-8 vs. UTF-16

UTF-8 is a variable-length encoding that can represent characters using one to four bytes.UTF-16 is a fixed-length encoding that uses two bytes to represent each character.
It uses 8 bits for each code unit.It uses 16 bits for each code unit.
UTF-8 is more compact for ASCII characters because it uses only one byte to represent them.However, UTF-16 takes up more space for ASCII characters because it uses two bytes for each character.
It can use up to four bytes to represent non-ASCII characters.It uses two bytes for most non-ASCII characters, but can use four bytes for some rare characters.
UTF-8 does not have endianness because it uses a single byte for each code unit.In contrast, UTF-16 can be big-endian or little-endian, depending on the byte order of the encoding.
The UTF-8’s byte order mark (BOM) is optional.The UTF-16’s byte order mark (BOM) is also optional.

What is UTF-8?

UTF-8 is a character encoding standard used for electronic communication. It is capable of encoding all possible characters in Unicode and uses one to four bytes to represent each character.

UTF-8 is widely used on the internet and supports almost all languages and characters in the world.

What is UTF-16?

UTF-16 (16-bit Unicode Transformation Format) is a character encoding capable of encoding all 1,112,064 valid code points of Unicode.

UTF-16 uses a variable-length encoding scheme that uses either one or two 16-bit code units to represent each Unicode code point. The first 65,536 code points (also known as the Basic Multilingual Plane or BMP) are represented by a single 16-bit code unit, while the remaining code points require two 16-bit code units.

Pros and cons of using UTF-8 and UTF-16



  • ASCII compatibility: All ASCII characters are encoded the same in UTF-8, which makes it easy to convert existing text files to UTF-8.
  • Smaller file size: In many cases, UTF-8 will result in a smaller file size than UTF-16.
  • Widespread support: UTF-8 is the most widely used encoding on the web, so there’s a good chance any software you use supports it.


  • Less efficient for Asian languages: Characters in Asian languages often take up more than one byte in UTF-8, which can result in slightly less efficient storage compared to UTF-16.



  • Supports a larger range of characters, including those outside of the BMP.
  • Efficient for languages that predominantly use characters within the BMP, such as CJK (Chinese, Japanese, Korean) languages.
  • Fixed-length encoding means faster processing and indexing of text.


  • Takes up more space than UTF-8 for characters within the BMP.
  • Not compatible with ASCII encoding, which can cause issues when working with legacy systems.
  • Endianness issues can occur when working with different computer architectures.

Examples of when to use each

UTF-8 is a variable width character encoding capable of encoding all 1,112,064 valid code points in Unicode using one to four 8-bit bytes. UTF-16 is a fixed-width character encoding that uses two 16-bit words to encode the most common 65,536 code points, and four 16-bit words to encode the rest of the 1,112,064 valid code points in Unicode.

UTF-8 is more space efficient than UTF-16 when storing English text because most characters in English can be represented with one byte whereas characters in other languages like Chinese or Japanese require two bytes in UTF-16.

However, UTF-16 is faster for applications to process because it doesn’t have to do any extra work to figure out how many bytes each character takes up.

In general, you should use UTF-8 unless you have a specific reason to use another character encoding like ASCII or EBCDIC. And even then, you should only use another encoding if your application requires it or if there’s a performance benefit to using something other than UTF-8.

Why is it important to understand the differences?

UTF-8 is a variable-width character encoding while UTF-16 is a fixed-width character encoding. This means that each character in a UTF-8 encoded string can take up anywhere from 1 to 4 bytes while each character in a UTF-16 encoded string will always take up 2 bytes.

For example, if you store all of your data inUTF-8 format, but then try to process it with a program that only supports UTF-16, you may end up with corrupted or incorrect data.

Key differences between UTF-8 and UTF-16

UTF-8 has the advantage of being able to represent any Unicode code point in a single byte, while UTF-16 always requires at least two bytes. This can be important when working with languages that use a lot of non-Latin characters, such as Chinese or Russian.

differences between UTF-8 and UTF-16

How do you choose which one to use?

The answer is: it depends on your needs. If you need to support a lot of languages and characters, then UTF-16 is a good choice. It can represent all Unicode characters, and it’s efficient for storage and transmission.

If you need to support fewer languages but still want good efficiency, then UTF-8 is a good choice. It can represent any Unicode character, but it’s more efficient for storage and transmission than UTF-16.

UTF-32 is less commonly used than the other two, but it has its advantages. It’s very easy to parse, for example. And if you need to support a lot of languages with very few characters (like Chinese), then UTF-32 can be more efficient than UTF-16.


UTF-8 is more space-efficient and compatible with ASCII, making it a good choice for web pages and databases that use mostly English text. On the other hand, UTF-16 provides support for a larger range of characters, making it ideal for handling text in languages with complex character sets.

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