The question of whether 120 Hz is the same as 120 frames per second (fps) is one of the most common points of confusion in modern displays and gaming. While the terms are often used interchangeably in casual conversation, they describe fundamentally different technical concepts that work together to create a smooth visual experience. Understanding the distinction is crucial for anyone making decisions about monitors, televisions, or gaming hardware.
Defining Refresh Rate: The Display's Cadence
Refresh rate, measured in Hertz (Hz), refers to how many times per second a display can physically redraw the entire screen image. A 120 Hz monitor updates its image 120 times every second, regardless of the content source. This physical capability is independent of any signal being received; the screen simply refreshes its state that many times per second. This rapid updating is the foundation for reducing visible flicker and enabling specific advanced technologies like strobing backlights aimed at reducing motion blur.
Defining Frame Rate: The Content's Pace
Frame rate, measured in frames per second (fps), refers to the frequency at which consecutive images, or frames, are produced by the source device. This is a characteristic of the content itself or the hardware generating it, such as a game engine or a camera. A game running at 60 fps is creating 60 unique images every second. If that stream is sent to a 120 Hz monitor, the display receives a new frame only half the time it is able to refresh its screen.
The Relationship Between the Two
The relationship between refresh rate and frame rate is analogous to a container (the display) and the liquid poured into it (the frames). The container can be larger than the amount of liquid available at any given moment. A 120 Hz display is the container with a high capacity, while 120 fps is the liquid filling that container. They are not identical; one is the potential capability of the hardware, and the other is the actual data being processed and sent to that hardware at a specific moment.
Why Mismatches Cause Visual Issues
When the refresh rate and frame rate are not synchronized, visual artifacts can occur. If a 60 fps output is displayed on a 120 Hz screen, the monitor often uses a technique called frame interpolation or simply displays each frame for two of its refresh cycles. This can sometimes result in a slight perceived softness or a "soap opera" effect that some viewers find unnatural. Conversely, if a high frame rate like 144 fps is sent to a 60 Hz display, the monitor cannot show all the frames, leading to screen tearing where parts of multiple frames are visible simultaneously.
The Goal: Synchronization for Smoothness
The ideal scenario for a smooth visual experience is when the frame rate matches or is a precise multiple of the refresh rate. This allows every frame to be displayed cleanly without tearing or duplication. Technologies like G-Sync and FreeSync were created to solve this problem dynamically. They adjust the monitor's refresh rate in real-time to match the output frame rate from the graphics card, eliminating tearing and minimizing stutter. Therefore, a 120 Hz monitor is optimized for a 120 fps output, but it is perfectly capable of displaying 60 fps, 30 fps, or other rates with the help of these adaptive sync technologies.
