Understand the Technical Characteristics of Smartphone Screens

What is screen refresh rate?

Screen refresh rate refers to the number of images that can be displayed on a screen in one second. It is expressed in hertz, which is equal to one second. Therefore, a 60Hz screen is capable of displaying 60 images in one second. The higher a screen's refresh rate, the more fluid and responsive it will be.

By July 2024, most smartphones should offer at least a 90Hz display. However, even smartphones under R$1,000, such as the Redmi 13C, offer 120Hz displays, some manufacturers, such as Google until very recently, or even Apple with its iPhone 15, still offer 60Hz displays.

A smartphone is never constantly at 120Hz, as the screen refresh rate adapts to the content displayed to optimize power consumption. For example, during a gaming session, the refresh rate can reach 120Hz to ensure optimal fluidity.

On the other hand, for static images or less dynamic content, the refresh rate can be reduced to lower levels, such as 10Hz or 60Hz, to conserve battery power while maintaining an enjoyable viewing experience.

For many people, the difference between 120Hz and 60Hz isn’t really noticeable, especially with the automatic refresh rate adjustment that adapts discreetly to the content. The visual experience remains smooth and pleasant, without you noticing a significant difference.

LTPO Technology

LTPO, which stands for Low Temperature Polycrystalline Oxide, is a display technology that dynamically adjusts the refresh rate of the screen. It saves power by reducing the refresh rate when smooth animations are not needed.

This technology has evolved over time, offering a wider range of refresh rate variations:

• LTPO 1.0: The first version allows you to adjust the refresh rate between a predefined range (for example, from 10Hz to 120Hz), but the transition is not as smooth or fast as in subsequent versions;
• LTPO 2.0: Introduced more recently, this version offers a smoother and faster transition between refresh rates, with a frequency range sometimes as low as 1 Hz, which further improves energy efficiency.

Understanding screen definition

Screen resolution, also known as resolution, is the number of pixels displayed on the screen, expressed as width × height (e.g. 1920 × 1080 pixels). The more pixels there are, the more detailed the image will be, making the screen sharper and more accurate.

To calculate the resolution of a screen, simply multiply the number of pixels in its width by the number of pixels in its height. For example, for a Full HD screen with a resolution of 1920×1080, there are a total of 2,073,600 pixels (1920×1080). This value indicates how many individual dots are used to create the image displayed on the screen.

If you know the size of your screen, you can also calculate the pixel density, which is measured in pixels per inch (PPI) and is calculated by dividing the diagonal in pixels by the diagonal in inches of the screen. In practice, for a 6.7-inch Full HD (1920×1080) screen, you will have a pixel density of 328.79 DPI.

Below we'll cover the main basics, but we'll only cover FHD or higher, as that's what most smartphones offer these days. You might also want to pay attention to “Nits,” which are a measure of how bright a screen is.

Definition explained

Full HD

FullHD is currently the standard for smartphone screen definition, although 2K (QHD) resolution is gaining ground in high-end smartphones.

Full HD resolution measures 1920 × 1080 pixels. Again, pixel density will depend on the overall size of the screen. On smartphones measuring around 6.67 inches, the pixel density is around 330.27 DPI.

QHD or 2K

QHD stands for QuadHD, which is four times the definition of standard HD. This means you can fit the same number of pixels as four HD displays onto a QHD display of the same size. The pixel measurement for QHD is 2560 × 1440 pixels. A 6.7-inch QHD display has a pixel density of 438.39 DPI. In comparison, the pixel density of a 5.5-inch Full-HD display is 400 DPI.

Definitions are also often referenced by the smallest number of pixels in the measurement. HD is sometimes referred to as 720p, Full HD as 1080p, and so on. With QHD, however, the name 2K comes from the fact that the largest pixel measurement is greater than 2000 pixels, which can be a bit confusing (and should really be called 2.5K, if we were being completely accurate).

Ultra HD or 4K

Much like 2K, the name 4K comes from the larger of the two pixel measurements, which is, technically speaking, 4096 pixels in 4K and just 3840 pixels in Ultra HD. So while these two terms are often used interchangeably, they are, in fact, quite different.

Ultra HD is 3860 × 2160 pixels, versus 4096 × 2160 for 4K. Both definitions are often abbreviated to 2160p, and the pixel difference is relatively small, but it does exist.

There are very few smartphones that offer a 4K display these days. Having pioneered 4K on smartphones with the Xperia Z5 Premium, the brand continues the tradition with its flagships, such as the Xperia 1 Mark V, which also offers a display in this resolution. Sony calls this display 4K, but it actually uses the smaller measurement of Ultra HD and not the “real” definition of what a 4K display is.

So which screen should you choose for your smartphone?

Whether it’s an entry-level, mid-range, or high-end smartphone, higher specs are always more appealing, and that’s totally understandable. However, keep in mind that specs aren’t everything in a device.

The best thing you can do is choose based on your needs. If you play AAA games, then a 120Hz or 144Hz display will obviously be more appealing. Otherwise, you can get away with a 90Hz setup. 60Hz displays are practically obsolete outside of Apple, so if you can, go for a higher refresh rate.

FullHD+ (FHD+) resolution is sufficient for most users today, offering sharp image quality for most daily uses, which explains why some high-end smartphones, such as the Pixel 8, are content with it. However, if you have the opportunity to have a screen with a better definition, do not hesitate, as it can improve your visual experience, especially for content rich in detail.