Here you go, this might help, I got it off of here, it comes in handy sometimes:
xlarge screens are at least 960dp x 720dp
large screens are at least 640dp x 480dp
normal screens are at least 470dp x 320dp
small screens are at least 426dp x 320dp
Generalised dpi values for screens:
ldpi resources for low-density (ldpi) screens (~120dpi)
mdpi resources for medium-density (mdpi) screens (~160dpi) (this is the baseline density)
hdpi resources for high-density (hdpi) screens (~240dpi)
xhdpi resources for extra high-density (xhdpi) screens (~320dpi)
Therefore generalised size of your resources (assuming they are full screen):
ldpi
Vertical = 426 * 120 / 160 = 319.5px
Horizontal = 320 * 120 / 160 = 240px
mdpi
Vertical = 470 * 160 / 160 = 470px
Horizontal = 320 * 160 / 160 = 320px
hdpi
Vertical = 640 * 240 / 160 = 960px
Horizontal = 480 * 240 / 160 = 720px
xhdpi
Vertical = 960 * 320 / 160 = 1920px
Horizontal = 720 * 320 / 160 = 1440px
Formula used:
px = dp*dpi/160