What is the maximum number of bytes for a UTF-8 encoded character?

utf-8 character-encoding byte character
Edd picture Edd · Mar 2, 2012 · Viewed 54.9k times · Source

What is the maximum number of bytes for a single UTF-8 encoded character?

I'll be encrypting the bytes of a String encoded in UTF-8 and therefore need to be able to work out the maximum number of bytes for a UTF-8 encoded String.

Could someone confirm the maximum number of bytes for a single UTF-8 encoded character please

Answer

Tamás picture Tamás · Mar 2, 2012

The maximum number of bytes per character is 4 according to RFC3629 which limited the character table to U+10FFFF:

In UTF-8, characters from the U+0000..U+10FFFF range (the UTF-16 accessible range) are encoded using sequences of 1 to 4 octets.

(The original specification allowed for up to six byte character codes for code points past U+10FFFF.)

Characters with a code less than 128 will require 1 byte only, and the next 1920 character codes require 2 bytes only. Unless you are working with an esoteric language, multiplying the character count by 4 will be a significant overestimation.

Related questions

Working with UTF-8 encoding in Python source

Consider: $ cat bla.py u = unicode('d…') s = u.encode('utf-8') print s $ python bla.py File "bla.py", line 1 SyntaxError: Non-ASCII character '\xe2' in file bla.py on line 1, but no encoding declared; see http://…

Read More
Setting the default Java character encoding

How do I properly set the default character encoding used by the JVM (1.5.x) programmatically? I have read that -Dfile.encoding=whatever used to be the way to go for older JVMs. I don't have that luxury for reasons I …

Read More
What's the difference between UTF-8 and UTF-8 without BOM?

What's different between UTF-8 and UTF-8 without a BOM? Which is better?

Read More