**njed**

**Thu, 21 Mar 2019 14:15:51 GMT**
## Good Day:
I'm a new user of Calca and am looking to define some custom units. From what I can tell, the system works well with units of the type: 1 ft = 12 inches, however I'm looking to do somewhat more complex conversions. For example: decibels referenced to one watt (dBW) is equal to decibels referenced to one milliwatt (dBm) plus a constant of 30.
consider the example:
1 ft in inches => 12 inches
defining this locally:
x = 12y
1 x in y => 12 y
dBW = dBm + 30
10 dBW in dBm => 10 dBm + 300
Is there a way to define a unit conversion that isn't a simple multiplication from one unit to another?
Thanks for any advice.