If you’re in the market for a new computer monitor or even a TV, you might be wondering about one of the metrics manufacturers tout about their panels, and that’s response time or response rate. Many advertise super-fast response times as low as 1ms. But what does that actually mean? And do their panels actually live up to that boast? We’ve got a crash course on everything you need to know right here.
To be clear, we’re covering this concept fairly simply so that you know what to look for when shopping around. A lot goes into a display’s response time, and it’s more complex than general TV and monitor shoppers need to know. If you want to dig deeper, monitor maker Viewsonic has a deep explanation of the concept that’s worth a look.
What is response time?
The short answer to this question is the time it takes for any given pixel to change from an origin state to a destination state. Even simpler: it measures how fast each frame changes.
This can be benchmarked through all sorts of methods: basic ones measure the time it takes to move from black to white, white to black, or black to white and back again, but the ones you’ll see touted the most are ones that go from one shade of gray to another or actual moving pictures – you’ll see these two metrics dubbed gray-to-gray (GtG or G2G) and Moving Picture Response Time (MPRT). There is no one agreed-upon standard when measuring either GtG or MPRT.
What’s the difference between response time and refresh rate?
The refresh rate is basically the capacity for your panel to update the picture data however many times per second. The response time has to do with the TV putting in the work to update that image by changing each pixel so that they turn from one shade of green, purple, or orange (you get the idea) to another shade of green, purple, orange, or a completely different color altogether. They’re separate metrics but have an important, sometimes intractable relationship: functionally, response times for changing a picture must be shorter than the time it takes to refresh the picture data.
Simply put, the refresh rate is how many FPS your screen can display. On the other hand, response time is a measure of how fast each frame can shift.
Imagine watching an extreme-slow-motion TV show that is exactly two frames in length. You’d spend a portion of your time watching all those pixels on the screen shift from one color to another (perhaps going through several other colors in the process). The remaining runtime should consist of either still frame that you could recognize as a proper image. When you speed that cycle up to something like 60 frames per second (16.67ms between frames), 90fps (11.11ms), or even 144Hz (6.94ms), your eyes will perceive slower responsiveness as visual aberrances such as motion blur. Practically speaking, the response time should never equal or exceed the maximum refresh rate of your TV lest all the visual information gets lost in constant transition.
Why does response time matter?
If response times edge close to the refresh rate, your eyes will spend much time watching those pixels in transition rather than in a still state. This will result in a form of motion blur where you perceive moving objects as leaving dark trails in their wake, called ghosting.
Other factors can also contribute to ghosting and deter from picture quality, such as when pixels overshoot a change and need to adjust back to the right color – in this case, the ghosting trail appears brighter than an item in motion. But of the basket of those factors, response time is high in priority.
You might think that a display’s response time also affects online gaming since, as NVIDIA says, “Frames Win Games.” With that in mind, you should consider the refresh rate as the bigger factor here since it dictates the data flow to your eyes. Good responsiveness might make it easier for your eyes to determine what to do with cleaner-looking frames – especially with over-sampled animations – but it’s not something you should put too much weight into since MMO servers have their own update or tick rates. Most of them run 60 cycles per second or less. Nearly every modern display on the market will be responsive enough to act within the 16.67ms between frame updates.
How to measure response time
One does not just measure response time. Okay, we’re half-kidding.
To test against the response time claims of manufacturers, sites like RTings and TFTCentral will set up a moving camera rig and monitor moving objects in sample videos to help determine how quickly pixels can shift to the correct color. These assessments can be aided with specialized hardware that can extract component-level results to a certain degree of confidence.
What types of TVs or monitors have the fastest response times?
There have been plenty of ups and downs with response times in the history of electronic displays. Still, regarding current-day options, the more expensive OLED panels (where the pixels self-illuminate) typically beat out LCD or LED TV options by wide margins in both GtG and MPRT figures. That’s not to say that you shouldn’t buy an LCD display or TV, though, since many of them will be able to satisfy standard 60fps viewing most times and, if need be, use nifty techniques to smooth out motion blur where it happens. But if you’re looking to get ahead of the curve for all the 120fps content you might want to watch, you should definitely favor OLED panels in your search.
As a reminder, response time isn’t the only metric you should be judging your next TV or monitor purchase, but it is one that generates confusion whenever people notice it.