Here is a list of options for “target-densityDpi”.
device-dpi: Use the device’s native dpi as target dpi.
medium-dpi: 160dpi, which is also the default as of today
high-dpi: 240dpi : We take any number between 70 and 400 as a valid target dpi
<meta name="viewport" content=" height = [pixel_value | device-height] , width = [pixel_value | device-width ] , initial-scale = float_value , minimum-scale = float_value , maximum-scale = float_value , user-scalable = [yes | no] , target-densitydpi = [dpi_value | device-dpi | high-dpi | medium-dpi | low-dpi] " />
<meta name=”viewport” content=”user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width, height=device-height, target-densitydpi=medium-dpi” />