The interesting character ranges are:<p><pre><code>  U+0000 to U+007F: 1 byte  for UTF-8, 2 for UTF-16
  U+0080 to U+07FF: 2 bytes for UTF-8 and UTF-16
  U+0800 to U+FFFF: 3 bytes for UTF-8, 2 for UTF-16
  U+10000 and up:   4 bytes for UTF-8 and UTF-16
</code></pre>
Arabic, Cyrillic (Russian), Tamil, Thai, Hebrew, and many other non-European scripts take an equal amount of space in either UTF-8 and UTF-16. Japanese and Korean have some cases where UTF-16 is more efficient, but only by a byte, and most Chinese characters take 4 bytes either way.