The Math::Units module converts a numeric value in one unit of measurement 
to some other unit. The units must be compatible, i.e. length can not be 
converted to volume. If a conversion can not be made an exception is 
thrown.

A combination chaining and reduction algorithm is used to perform the most 
direct unit conversion possible. Units may be written in several different 
styles. An abbreviation table is used to convert from common long-form 
unit names to the (more or less) standard abbreviations that the units 
module uses internally. All multiplicative unit conversions are cached so 
that future conversions can be performed very quickly.

Too many units, prefixes and abbreviations are supported to list here. See 
the source code for a complete listing.

WWW: http://search.cpan.org/dist/Math-Units/