Detailed explanation of the length units in Android include DP, SP, PX, In, PT, and mm

Many netizens do not quite understand the difference between DP, SP, and PX: here we will introduce DP and sp. DP is dip. This is basically similar to sp. You can use DP or SP to specify attributes such as length and height. If you set the font, you need to use sp. DP is not related to density. SP is not only related to density, but also to scale. If the screen density is 160, DP and SP are the same as PX. 1dp = 1sp = 1px, but if PX is used as the unit, if the screen size remains unchanged (assuming it is still 3.2), the screen density is changed to 320. The original textview width is set to 320 PX, And the 3.2-inch screen with a density of 160 is half shorter than the 3.2-inch screen with a density. But if it is set to 160dp or 160sp. The system automatically sets the width property value to 320px. That is, 160*320/160. Among them, 320/160 can be called the density proportion factor. That is to say, if DP and SP are used, the system will automatically convert according to the screen density change.

Next, let's take a look at the meaning of other units.

Px: the actual pixel of the screen. For example, 320*480 screens have 320 pixels horizontally and 480 pixels vertically.

In: indicates the inch, which is the physical size of the screen. Each inch equals 2.54 cm. For example, the screen size of a mobile phone is often described as 3.2 (English), 3.5 (English), and 4 (English. These dimensions are the diagonal length of the screen. If the phone screen is 3.2 inch, the diagonal line length of the phone screen (visible area) is 3.2*2.54 = 8.128 cm. You can measure your mobile phone screen to see if the size is the same as the actual size.

MM: Indicates mm, which is the physical size of the screen.

PT: indicates a point, which is the physical size of the screen. The size is 1 inch of 1/72.