Generalized rule for pixel values to support multiple screen is based on a baseline configuration of your device screen density. Baseline for density 160 pixels , mdpi comes in this range. So by calculating dpi values you can put these values in different dimens.xml to support various devices. General formula is :
Result = Value(dpi) * device density(pi)/160(dpi)
So first check your device density first then according to above formula calculate the values for dimens.xml. For standard we generally assume that:
For mdpi density = 160, hdpi - 240, xhdpi - 320 , ldpi - 120
As in your case if value is 10*10 then the Result for different screen will be :
For ldpi:
Result = 10*120/160 = 7.5 , i.e 7 pixels
For mdpi:
Result = 10*160/160 = 10 pixels
For hdpi:
Result = 10*240/160 = 15 pixels
For xhdpi:
Result = 10*320/160 = 20 pixels
You can also refer to this http://developer.android.com/guide/practices/screens_support.html and http://developer.android.com/training/multiscreen/screendensities.html
