Taken from this SO thread
- px is one pixel.
- sp is scale-independent pixels
- dip (dp) is Density-independent pixels.
Use
- sp for font sizes
- dp for everything else
From Android Developer
+---------+-------------+---------------+-------------+--------------------+
| Density | Description | Units Per | Density | Same Physical Size |
| | | Physical Inch | Independent | On Every Screen |
+---------+-------------+---------------+-------------+--------------------+
| px | Pixels | Varies | No | No |
+---------+-------------+---------------+-------------+--------------------+
| in | Inches | 1 | Yes | Yes |
+---------+-------------+---------------+-------------+--------------------+
| mm | Millimeters | 24.5 | Yes | Yes |
+---------+-------------+---------------+-------------+--------------------+
| pt | Points | 72 | Yes | Yes |
+---------+-------------+---------------+-------------+--------------------+
| dp | Density | ~ 160 | Yes | No |
| | Independent | | | |
| | Pixels | | | |
+---------+-------------+---------------+-------------+--------------------+
| sp | Scale | ~ 160 | Yes | No |
| | Independent | | | |
| | Pixels | | | |
+---------+-------------+---------------+-------------+--------------------+
px Pixels - corresponds to actual pixels on the screen.
in Inches - based on the physical size of the screen. 1 Inch = 2.54
centimeters
mm Millimeters - based on the physical size of the screen.
pt Points - 1/72 of an inch based on the physical size of the screen.
dp Density-independent Pixels - an abstract unit that is based on the
physical density of the screen. These units are relative to a 160 dpi
screen, so one dp is one pixel on a 160 dpi screen. The ratio of
dp-to-pixel will change with the screen density, but not necessarily
in direct proportion. Note: The compiler accepts both "dip" and "dp",
though "dp" is more consistent with "sp".
sp Scale-independent Pixels - this is like the dp unit, but it is also
scaled by the user's font size preference. It is recommend you use
this unit when specifying font sizes, so they will be adjusted for
both the screen density and user's preference.
Check out this SO thread aswell. (Changing px to dp programmatically)
