Video Frame Rate vs. Screen Refresh Rate

What's the difference between FPS and Hz?

Two images of a snowboarder side by side; left one is blurry with motion, the other is in focus

Sony 

When shopping for a TV, it's easy to get overwhelmed by terms like progressive scanning, 4K Ultra HD, frame rates, and screen refresh rates. While those last two sound like the same thing, there's a subtle difference between them, which is why we've compiled a guide to the differences between Hz vs. FPS.

Frame Rate
  • Refers to the number of frames displayed every second.

  • Measured in FPS (frames per second)

Refresh Rate
  • Refers to how many times the display refreshes per second.

  • Measured in Hz (hertz).

Frame Rate

Just like traditional film, digital videos display images as individual frames. Frame rate refers to the number of frames-per-second (FPS) a television can display. These frames are displayed using the interlaced scan method or the progressive scan method. Frame rates are often listed alongside the video resolution. For example, a 1080p/60 TV has a frame rate of 60 FPS.

Refresh Rate

Refresh rate represents how many times the display is completely reconstructed every second. The more times the screen is "refreshed," the smoother the image is in terms of motion rendering and flicker reduction.

Refresh rates are measured in hertz (Hz). For example, a television with a 60 Hz refresh rate represents a complete reconstruction of the screen image 60 times every second. If the video is rendered at 30 FPS, then each video frame is repeated twice.

Backlight Scanning

One technique that some TV manufacturers use to reduce motion blur is referred to as backlight scanning, in which a backlight flashes on and off rapidly between each screen refresh. If a TV has a 120 Hz screen refresh rate, backlight scanning delivers the effect of having a 240 Hz screen refresh rate. This feature can usually be enabled or disabled separately from the screen refresh rate setting.

Motion or Frame Interpolation

Another feature similar to backlight scanning is motion or frame interpolation. This technique entails the video processor combining elements of successive frames to blend them together for smoother motion rendering. The downside of this effect is that it can make movies shot on film look like they were shot on video.

Enhanced refresh rates, backlight scanning, and motion/frame interpolation apply primarily to LCD and LED/LCD TVs. Plasma TVs handle motion processing differently, utilizing a technology referred to as a Sub-Field Drive.

1080p/24 Media Players

Since film is shot at 24 frames per second, the original 24 frames must be converted to display on a typical television screen. However, with the introduction of Blu-ray Disc and HD-DVD players that can actually output a 24 frame per second video signal, new refresh rates have been implemented to accommodate these signals in the correct mathematical ratio.

If a TV is 1080p/60 or 1080p/30-only compatible, it would not accept the 1080p/24 input. However, most Blu-ray Disc and HD-DVD players convert the outgoing signal to either 1080p/60 or 1080i/30 so that the information can be processed by a TV properly for screen display if it is not compatible with 1080p/24.

Final Verdict

In order to market TVs that use faster refresh rates, manufacturers have created their own buzzwords to draw the consumer in with less intimidating non-technical jargon. For example, LG uses the label TruMotion, Panasonic uses Intelligent Frame Creation, Samsung uses Auto Motion Plus or Clear Motion Rate (CMR), Sharp uses AquoMotion, Sony uses MotionFlow, Toshiba uses ClearScan, and Vizio uses SmoothMotion.

Don't get too bogged down with the numbers and terminology. Let your own eyes be your guide as you compare TV displays. Just make sure the TV is powerful enough to support your media players and video game consoles. For example, to play video games in 4K and 60 FPS, you need a TV capable of displaying high resolutions and fast frame rates.