Android Launcher Icon Design Guidelines

LDPI should be 36 x 36.

MDPI should be 48 x 48.

TVDPI should be 64 x 64.

HDPI should be 72 x 72.

XHDPI should be 96 x 96.

XXHDPI should be 144 x 144.

XXXHDPI should be 192 x 192.

Basic Formula :

Basically, all of the other icons should be in proportion to the 'baseline' icon

MDPI at 48 x 48.

LDPI is MDPI x 0.75.

HDPI is MDPI x 1.5.

TVDPI is MDPI x 1.33.

XHDPI is MDPI x 2.

XXHDPI is MDPI x 3.

XXXHDPI is MDPI x 4.

example:

so lets take an image with about the size of 100X100:

for mdpi it should be 100X100
for ldpi it should be 75X75
for hdpi it should be 150X150
for xhdpi it should be 200X200
for xxhdpi it should be 300X300
for xxxhdpi it should be 400X400

For more Details visit on official site of android :Here