I haven’t really noticed before but Spotlight has been able to do Calculations for a while now. Since Yosemite it can now also do Unit conversions.
It’s a nice feature because you don’t need to specify which conversion that you want, spotlight will give you the conversion it thinks you need and also a number of additional suggestions as well!
You can Convert Area, Currency, Energy, Length, Power, Pressure, Speed, Temperature, Time, Volume and Weights
 |
 |
 |
 |
 |
 |