A utility to convert Unicode characters to decimal and hexadecimal HTML entities.
(by Shaun Moss, adapted from: ASCII to HEX to Unicode Converter by Mike Golding)
The partial conversions do not convert characters with a code of 127 or less, (i.e. plain old ASCII characters), which can appear in HTML code as they are.
More about character sets.
I usually use 'partial decimal' for HTML code. I have noticed some quirkiness with the hexadecimal codes - sometimes the HTML entity is not converted to the character and appears on the page unconverted (e.g. 월 instead of 월). Also, although some text editors will allow you to type Latin 1 characters (e.g. é, ç) into your HTML code, these characters do not always render properly (not sure why, if you know please email me). For maximum reliability use decimal HTML entities for any non-ASCII characters.
Check out Month and Day Names in 14 Langauges to see these HTML entities in action.