Are you Android developer or Designer?
Let download "DP / PX Converter" App.
Useful for planners, developers, and designers who need to calculate the screen size of their phones.

DP / PX Converter is very simple to use.
The result will show all values from from Low Density, Medium Density, High Density, Extra High Density, Extra Extra High Density, Extra Extra Extra High Density.

■ Information about DPI
Low Density (120dpi, ldpi, 0.75x)
Medium Density BASELINE (160dpi, mdpi, 1x)
High Density (240dpi, hdpi, 1.5x)
Extra High Density (320dpi, xhdpi, 2x)
Extra Extra High Density (480dpi, xxhdpi, 3x)
Extra Extra Extra High Density (640dpi, xxxhdpi, 4x)

https://developer.android.com/training/multiscreen/screendensities