There’s a myriad of mobile devices to select. When developing an application for smartphones, it’s critical to stay current and create the best experience across all devices. Screen size and screen resolution are two factors to consider before, during, and after developing a mobile application. This article explains the differences between the two and provides all the information you need to know in a nutshell.

Explanation of screen size and screen resolution

The terms “screen resolution” as well as “screen size” are often used interchangeably. They both might seem confusing when designing your mobile application. But they both are also very important elements that will affect your application layout.

What do screen size and screen resolution mean?

Screen size is the diagonal of the viewable screen (physical measurement of it).

Screen resolution is the number of pixels on particular screen size.

While a screen’s resolution can be adjusted affecting visual quality, the screen size is fixed and cannot be changed. App developers would be unable to design for every available mobile device on the market as there’s plenty of them. Instead of that, designers just divide the style into standardized smartphone or tablet sizes. All of this is about matching visuals to the device.

Why size and resolution are important for designing?

Understanding the size and resolution of mobile applications can help you optimize them for many devices. This includes smartphones, tablets, smart TVs, or any other target devices where your software should be available. Moreover, applications that do not respect particular requirements (like Apple’s size and screen resolution rules), will not be allowed in app stores. Building an app with numerous screen sizes in mind can’t be an afterthought in today’s digital environment.

Screen Resolution & Screen Size mobile app

Common terminology used during mobile app design

As previously mentioned, screen resolution and size are two essential components that influence an app’s overall layout and structure. Now let’s take a look at the most frequent terms that you may hear used to describe size and resolution.


Pixels are the smallest pieces that make a display, which is short for picture elements. The resolution of an image is determined by the number of pixels in it. A pixel has no physical representation itself as it can only convey value through interaction with the size of the screen.

Every pixel has a color, and the picture is made up of all the pixels. A pixel’s color can be stored using a mix of red, green, and blue (RGB), but other colors, such as cyan, magenta, yellow, and black, are also featured (CMYK).


Points are a resolution measurement on the iPhones. Depending on the density, a point can include many pixels. Keep in mind that pixels and points are not the same things. This is a measurement unit. App designers often consider points but the design should be in pixels. 


Pixel density, often known as pixels per inch (PPI), is a measurement of display resolution that is related to the size in inches. It’s not the same as resolution as pixel density refers to the level of detail on the device. PPI is significant because it indicates how effectively an image will display on a particular screen. Mobile devices have small screens, however, modern smartphones have a higher PPI rating – around 250-800 PPI and up to 4K display. Because higher resolution displays have a higher pixel density, they require images with a larger pixel count.


When describing the resolutions, the term DPI is often mistakenly used instead of PPI. These are two different units. DPI is short for dots per inch. It describes the amount of ink dots on a printed image while PPI refers to the pixels on the digital display.

Screen sizes and orientations

On the same mobile platform, sizes and resolutions might differ. If you want the application to look consistent on different devices, the user interface has to be scalable. Aside from that, there are many sorts of screens so there might be a situation when you have to adjust designs for particular screens a bit more – add some extra background, or reduce the spacing. It always depends on the specific design, possibilities that remain consistent with a product’s design and your requirements. The size takes into account factors such as screen orientation, UI components (like navigation), and window configurations. 

From portrait to landscape

Screen Resolution & Screen Size portrait vs landscape phone

The accelerometer integrated into modern smart devices might be used to align the screen based on the device’s orientation, such as when switching between portrait and landscape modes. Because it gives an additional layout with a simple rotation of a device and without pushing unnecessary buttons, capability like that provides enormous flexibility to develop an improved user experience.

When designing for mobile devices, consider the environment and situations in which an application will be used when designing for smartphones.

Common display resolutions

When it comes to the mobile app market, it’s always crucial to know which devices are most popular. While there is no single perfect size, some resolutions appear considerably more frequently than others. When creating, pay special attention to the resolution ranges because these are the ones you can be sure will be used on a variety of devices. Some of the most frequent resolution options are as follows:

  • Monitor displays ranging from 1024×768 to 1920×1080,
  • Smartphone displays ranging from 360×640 to 414×896,
  • Tablet displays ranging from 601×962 to 1280×800.


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Designing an app for mobile devices

The goal of screen resolution and size is to make an app visually suitable for every Android or iOS device. The user experience is going to be ruined if you develop an app with only one screen in mind. This is something that every mobile digital product should avoid at all costs. For your app to be successful, you should become aware of the way to design it right.