What is the difference between px, dip, dp, and sp?

user_235885 0
Viewed 1421879

What is the difference between the units of measure px, dip, dp, and sp?

dimension android-layout units-of-measurement android user-interface
33 Answers

From the Android Developer Documentation:

  1. px
    Pixels - corresponds to actual pixels on the screen.

  2. in
    Inches - based on the physical size of the screen.
    1 Inch OR 2.54 centimeters

  3. mm
    > Millimeters - based on the physical size of the screen.

  4. pt
    > Points - 1/72 of an inch based on the physical size of the screen.

  5. dp or dip
    > 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".

  6. sp
    > Scaleable Pixels OR scale-independent pixels - this is like the dp unit, but it is also scaled by the user's font size preference. It is recommended you use this unit when specifying font sizes, so they will be adjusted for both the screen density and the user's preference. Note, the Android documentation is inconsistent on what sp actually stands for, one doc says "scale-independent pixels", the other says "scaleable pixels".

From Understanding Density Independence In Android:

Density Bucket Screen Density Physical Size Pixel Size
ldpi 120 dpi 0.5 x 0.5 in 0.5 in * 120 dpi = 60x60 px
mdpi 160 dpi 0.5 x 0.5 in 0.5 in * 160 dpi = 80x80 px
hdpi 240 dpi 0.5 x 0.5 in 0.5 in * 240 dpi = 120x120 px
xhdpi 320 dpi 0.5 x 0.5 in 0.5 in * 320 dpi = 160x160 px
xxhdpi 480 dpi 0.5 x 0.5 in 0.5 in * 480 dpi = 240x240 px
xxxhdpi 640 dpi 0.5 x 0.5 in 0.5 in * 640 dpi = 320x320 px
Unit Description Units Per Physical Inch Density Independent? Same Physical Size On Every Screen?
px Pixels Varies No No
in Inches 1 Yes Yes
mm Millimeters 25.4 Yes Yes
pt Points 72 Yes Yes
dp Density Independent Pixels ~160 Yes No
sp Scale Independent Pixels ~160 Yes No

More info can be also be found in the Google Design Documentation.

user_1767610

Pixel density

Screen pixel density and resolution vary depending on the platform. Device-independent pixels and scalable pixels are units that provide a flexible way to accommodate a design across platforms.

Calculating pixel density

The number of pixels that fit into an inch is referred to as pixel density. High-density screens have more pixels per inch than low-density ones...

The number of pixels that fit into an inch is referred to as pixel density. High-density screens have more pixels per inch than low-density ones. As a result, UI elements of the same pixel dimensions appear larger on low-density screens, and smaller on high-density screens.

To calculate screen density, you can use this equation:

Screen density = Screen width (or height) in pixels / Screen width (or height) in inches

Hight density vs lower density displays

Density independence

Screen pixel density and resolution vary depending on the platform. Device-independent pixels and scalable pixels are units that provide a flexible way to accommodate a design across platforms.

Calculating pixel density The number of pixels that fit into an inch is referred to as pixel density. High-density screens have more pixels per inch than low-density ones...

Density independence refers to the uniform display of UI elements on screens with different densities.

Density-independent pixels, written as dp (pronounced “dips”), are flexible units that scale to have uniform dimensions on any screen. Material UIs use density-independent pixels to display elements consistently on screens with different densities.

  1. Low-density screen displayed with density independence
  2. High-density screen displayed with density independence

Read full text https://material.io/design/layout/pixel-density.html

user_79459300

px = means pixels on a screen for pixel calculation px = dp * (dpi / 160) can be used dip = Density-independent Pixels which is equal to dp sp = should only be use for text

user_103096930
Related