60, 90 or 120 Hertz?
By Adrian Mühlroth | May 05, 2022 at 8:00 p.m
Anyone who buys a television or a smartphone cannot avoid the refresh rate in Hertz. But what does it actually mean – and how many Hertz do you really need? TECHBOOK explains the Hertz confusion.
100, 120, 400 or even 800 Hertz? Anyone who buys a television or a smartphone is confronted with the refresh rate in addition to key figures such as the size in inches or the luminosity in nits. But is the screen really better if it has more Hertz? TECHBOOK checks the myth.
What does "hertz" actually mean?
The Hertz unit designates the frequency, in the case of screens the refresh rate. A screen with 50 Hertz can transmit 50 frames per second. To clarify: like a flip book, a moving image consists of many different individual images that are quickly strung together. This creates a fluid movement for the viewer.
On German television, however, films run at 24 frames per second – but why are there televisions with allegedly 400 Hertz and more?
In a nutshell
What is the difference between Hertz and FPS?
The Hertz number only indicates how many frames per second a television or monitor can display. FPS stands for frames per second and, in contrast, refers to the speed at which a graphics card or graphics unit can produce images. For example, if a graphics card outputs 120 FPS and the screen only supports 90 Hertz, the excess 30 FPS will be lost.
What is the point of a high Hertz number?
In smartphones, a high Hertz number on the screen ensures that the content and animations shown look extremely smooth. The effect is often described as "velvety" because there is no jerking in the display. Movements appear more natural and simply faster. Modern smartphones often have screens between 90 Hz and 144 Hz.
In TV sets, a high hertz number also has a positive effect. The processors in the TV set simply calculate a few more intermediate frames and artificially drive the hertz number up. Why? Christian Trozinski, editor-in-chief of the specialist magazine "HDTV Magazin", explains in an interview with TECHBOOK: "Even a 24 Hertz signal could be displayed very sharply without interframe calculation, but then the image could flicker very strongly and it would not run completely smoothly. At the moment, a high Hz number means: Thanks to the interframe calculation, moving image scenes are displayed sharply, smoothly and at the same time without flickering.”
However, there is also a disadvantage, the so-called "soap opera effect": If the intermediate images are calculated with little detail and with a pure focus on the movement, the backgrounds in films and series can sometimes appear somewhat static – similar to cheaply produced soap operas.
The right frame rate for the respective purpose
When it comes to smartphones, it also depends on the primary purpose. For a noticeable effect, we recommend using a 120 Hz panel. But be careful: the higher refresh rate has a negative effect on the battery life, since the smartphone has to calculate more images.