How to convert file format from ASCII to UTF

How to convert file format from ASCII to UTF

#1 : Check the file format
$file input.txt

#2
use the iconv command
iconv -f   <<Source Format >>    -t      <<Target Format>>   < input.txt   > output.txt

iconv -f ASCII  -t UTF8   < input.txt   > output.txt

#3 #1 : Check the file format
$file output.txt