The Difference Between Refresh Rate and Frames per Second


The science behind computer monitors and televisions is often difficult to understand, primarily due to how the companies who make these products advertise them. Everything from “our TV has a contrast ratio of 1-million-to-1” and “our monitor is 120Hz” (when it’s just a 60Hz TV with a scanning backlight causing you to see the same frame twice in a row) can lead the unassuming customer into believing that a display is top-of-the-line when it really isn’t. In the gaming/editing community, our monitors are just as important as the rig which connects to them. So, to further advance my knowledge of screen technology, I figured I would start by researching and discussing the difference between FPS and Hz.

Frames per second (FPS) is how many frames your graphics card can create every second or how many frames per second of a moving picture can be displayed.

The refresh rate (Hz) is how many times your monitor refreshes a display to show a new frame in a second; it is entirely independent of frames per second since you still have refreshes with a static image.

You should theoretically be able to see all the frames that have been drawn if your graphics card is producing the same or fewer frames from what the refresh rate is; this is what Nvidia’s Gsync and AMD’s FreeSync technologies achieve by synchronizing the framerate of the card with the refresh rate of the monitor. So, the graphics card is drawing each frame at the exact moment the monitor is ready to display a new one which makes the response rate effectively zero.

Computer/console graphics cards are designed to calculate and move pixels into what’s known as a frame buffer (framestore). The graphics card gets the texture data, model geometry, lighting, viewpoint info (what you’re looking at), movement, etc. from the CPU/RAM and then calculates for each pixel in the frame buffer. What color and brightness it should be is based on everything happening in the screen view. How high your graphics are set and how much is going on in your game or program will impact how fast the graphics card can update this frame buffer. Once a frame is finished, the GPU toggles a switch and instructs the HDMI port to send this to your screen. If there’s too much going on in your game/program, your GPU will only update the frame buffer maybe 20-30 times per second.

So, that means if your monitor is running at 72 Hz, it will display the same frame for 2-3 updates – i.e., until the next frame is ready from the GPU; this results in only a 20-30Hz screen update. More frames per second offer smoother, cleaner, and more lifelike images.

If you have a high-end (or multiple) GPUs and you’re getting 100+ fps, but only have a 60 Hz monitor, you’re not getting the full potential out of your computer; if this is the case, you should crank up the graphics settings.

Frame rates in VR are entirely different since every frame must be generally drawn twice (for each eye). Using lower frame rates, VR can give motion sickness to users due to jumping and stuttering frames. With VR’s requirement for high frame rates, a computer or console’s hardware must be powerful enough to keep up with VR’s high frame rate demand.

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