Hi,
Check out this new site for constants calculations and unit conversions with suggest list and users can add constants and conversion after the admin approves them.
http://fermion.website.org
you calculate a conversion by typing: 1{kg}{g} i.e. the amount to convert followed by the base unit in curly braces and then the unit we want to be converted into also in {}.
by pressing 1{k it will give you the list of units with the letter k, so it's very easy to get what you want.
you can even do something like 1{m*sec^-1}{km,hour} you get the conversion of 1 m/sec to km per hour.
or 9.8{m*sec^-2}{ft} will give you this output: 9.8 m·sec-2 = 32.15223102 ft·sec-2
i.e. it converted the acceleration in m/sec^2 to ft/sec^2.
check it out it's really cool and useful.
http://fermion.website.org
Thanks.