One of the many confusing aspects of buying a new TV is trying to understand the technical specifications that the TV manufacturers tell us.
One of the most common ones is the TV refresh rate. We get told this TV has a refresh rate of 120 Hz. 240 Hz. 480 Hz. More!
So, which is the best refresh rate for a TV? The bigger number is better right? Well, not as much as you might think. And, in many cases, not at all.
So, let us try to understand the refresh rates of LED and OLED TVs, and answer some of the most common questions. It is a complex subject, and I’m not a scientist.
But, I’ll try to explain the most important points in words I can understand. Hopefully, you will too.
What Is the Refresh Rate of a TV?
The refresh rate of a TV is the number of times per second the picture is ‘redrawn’. Or, to put it another way, how many images it can show in one second.
The quicker a picture is refreshed, then it should help any motion to appear smoother to the human eye – and to have less flicker.
This is a good thing.
Video Frame Rates vs TV Refresh Rates
First up, it’s a good idea to understand the difference between the frame rate of a video recording and the refresh rate of your TV.
They are two different things but influence each other.
As you probably know, video recordings capture live action by taking a series of still images – or frames.
If these frames are close enough together in time, then we will see this as smooth motion when played back.
Historically, the frame rate of analog video was based on the frequency of the local power supply.
This means that it was different around the world:
- PAL regions (UK, much of Europe) – 25 frames per second
- NTSC regions (North America, Japan) – 29.97 frames per second
To save bandwidth during transmission, analog video was always interlaced.
This means that a single frame was divided into two fields containing the odd numbered lines and the even numbered lines of the image. The TV screen would then display these fields in the correct order to play the video.
Therefore, in PAL regions, the frequency of interlaced video was 50 Hertz (Hz):
25 frames per second x 2 fields = 50 fields per second
In NTSC regions, the frequency of interlaced video was 59.94 Hertz:
29.97 frames per second x 2 fields = 59.94 fields per second
*** There is plenty of confusion about the NTSC 29.97 and 59.94 frame rates. Many people just round these up to 30 and 60 frames per second. This isn’t actually correct, as modern HD cameras can record at 29.97 or 30 and 59.94 or 60 frames per second. So, they are actually two distinct rates. However, just to add to the confusion (and make things easier), from now on I’ll just talk about 30 and 60 Hz. ***
By the way, Hertz is a standard for describing the frequency of something i.e. the number of cycles per second. It can be used to describe the frequency of anything, not just video frame rates.
Why Are Movies Filmed at 24 Frames per Second?
Content recorded on film is traditionally recorded at 24 frames per second (fps). This still holds today – although some movies have been shot in higher frame rates.
Why is this different from video frame rates?
Simply because when movies were first made this was the lowest frame rate that was considered suitable for viewing.
It was easier (and cheaper) to build and use the hardware to film and display movies. And it looked good enough to the human eye to be realistic.
It hasn’t changed much over time because we have become used to watching movies at 24 frames per second. It ‘looks like a movie’ at this frame rate – and most people prefer it.
So that’s what the video refresh rate is. What about the refresh rate of our TV screen?
Well, due to the standard video frame rates that we’ve just discussed, televisions were designed with a refresh rate to match the frequency of the video transmissions.
So, TVs in PAL regions had a 50 Hz refresh rate, and TVs in NTSC regions had a 60 Hz refresh rate.
Now, these frame rates were developed for analog TV systems. Even so, they’ve remained the standard even with the new digital broadcasting systems – ATSC in the US and DVB in Europe.
Modern broadcast video standards support a few different frame rates. The most common are:
- 24p: 24 progressive frames per second.
- 25p: 25 progressive frames per second.
- 30p: 30 progressive frames per second.
- 50i: 25 interlaced frames per second.
- 60i: 30 interlaced frames per second.
- 50p: 50 progressive frames per second.
- 60p: 60 progressive frames per second.
The frame rate is sometimes added to the end of the TV picture resolution to describe the frame rate used:
- 1080p30: 1080p picture with a 30 Hz frame rate
- 1080p60: 1080p picture with a 60 Hz frame rate
The higher video frame rate will display smoother motion as there are more frames to capture it. This is what determines how smooth the motion will appear on your TV – not the TV refresh rate.
The TV is just displaying what has originally been captured on the video.
Refresh Rates for Modern Flat Screen TVs
So, now we understand that the standard refresh rate of TVs is either 50 Hz or 60 Hz, why do we see different TV refresh rates quoted when we go to buy a new TV?
You can see quoted refresh rates of 120 Hz, 240 Hz, 480 Hz and more.
To begin with, you should understand that the maximum native refresh rate of a modern flat screen TV today is 120 Hz.
This means it can display 120 images every second.
So, the TV you buy will either have a 120 Hz refresh rate – or the older standard of 60 Hz.
In Europe, this will more likely be 50 Hz or 100 Hz – although a modern TV in this region will often support 60/120 Hz too.
So, if you are looking for the TV with the highest refresh rate, the answer is that most of them are the same as each other.
Anything that you see as being higher than this is marketing hype designed to make you buy a ‘better’ TV.
The bigger number must be better, right?
I’ll discuss these higher refresh rates later.
60 Hz vs 120 Hz TVs
So, is a 120 Hz TV better than a 60 Hz TV?
The obvious conclusion is that a TV with a 120 Hz refresh rate will display a smoother image.
However, it’s not as simple as that.
We also need to consider the frequency of the content that is going to be displayed on the TV.
And, we now know that the frame rate of the content, and the refresh rate of the TV, are two different things.
If we take a video recorded at 60p, then to display this image on a 120 Hz TV, each frame is repeated twice:
60 fps x 2 = 120 fps
For a 30p video, we just repeat the same frames 4 times:
30 fps x 4 = 120 fps
However, this makes no difference to how smooth the image looks. There is no increase in detail of the movement.
Your 120 Hz TV is just showing you the same frames that you would see on a 60 Hz TV.
Also, when you input a 60 Hz video, some 120 Hz TVs will just switch to a 60 Hz refresh rate. So, again, no difference to a standard 60 Hz TV.
So, does this mean that there is no point in buying a 120 Hz TV?
No, I wouldn’t go that far, but it does mean that the benefits are not going to be as great as you might think.
The main benefits of a 120 Hz TV are:
- some video content and games are made with higher frame rates. Therefore, the TV can display them as intended. However, the HDMI inputs on your TV are probably locked to 60 Hz. This is the current limit of the HDMI 2.0 specification. The new HDMI 2.1 specification does support 4K and 8K video at 120 Hz.
- movies are made at 24 Hz. In some instances, they can look smoother on a 120 Hz TV. This is because each frame can be repeated 5 times to mirror the 120 Hz refresh rate – 24 fps x 5 = 120. On a 60 Hz TV, “3:2 pulldown” is used to display the movie. This can cause judder on some shots where a slow panning scene may appear to jump. This is because the 24 fps of the movie can’t be easily divided into the 30 fps used for NTSC video. So, frames are repeated, but not in an even manner. However, many TVs just adjust their refresh rate to 24 Hz to play a movie, so the higher rate doesn’t make any difference.
- a 120 Hz TV can add motion interpolation to a 60 Hz source. This is because it has a higher refresh rate to display the extra interpolated frames. A 60 Hz TV can’t interpolate a 60 Hz source because it can’t show more than 60 frames per second. It can only interpolate a source with a lower rate than 60 Hz. This benefit is only useful if you like the look of the ‘soap opera effect’. Motion interpolation is described in more detail below.
- some TVs are prone to motion blur. This is where the image appears to blur when displaying fast-moving content like games and sports. This annoys some people more than others. A higher refresh rate can help to reduce motion blur when used with various processing techniques. However, motion blur is caused by several factors, and the refresh rate of the TV will have little effect on these. See the description of motion blur on TV screens later in the article.
- if you are sensitive to flicker, then a TV with a faster refresh rate should help.
So, while there are some benefits of a 120 Hz TV, you may not find many of them that useful in your day-to-day viewing.
Now, if you are buying a new TV, you may not have a choice what you get anyway.
The refresh rate on a 4K TV will often be 120 Hz. Even though some will claim to have more!
Cheaper models may only be 60 Hz.
In my guide to the best OLED and LED flat screen TVs in 2021, I include the refresh rates of the featured models.
So, how do we explain the higher refresh rates of 240 Hz and above?
240 Hz & 480 Hz Refresh Rate TVs
You might see a TV advertised with a refresh rate of 240 Hz. Good, huh?
No, because it isn’t.
A refresh rate of 480 Hz? Wow, that sounds great!
Except, it isn’t really.
As mentioned previously, there are currently only two actual refresh rates for TVs in the US – 60 Hz and 120 Hz.
These are native refresh rates i.e. the rate at which the TV can actually refresh the screen.
Anything else you see is marketing smoke and mirrors released by the manufacturer to make their TV more appealing.
These ‘increased’ refresh rates are just inflated numbers that can only be realized by the TV processing the picture.
Each manufacturer has their own name for this processing:
- Samsung – Motion Rate
- Sony – Motion Flow XR
- LG – TruMotion
- Vizio – Effective Refresh Rate
- Toshiba – Clear Frame
- Sharp – AquoMotion
- TCL – Clear Motion Index
Each of these is used to claim a refresh rate higher than the actual figure for the TV. Which makes it very difficult to compare like-with-like.
For example, with Samsung, a motion rate of 120 for a 4K TV will have a native refresh rate of 60 Hz.
A 4K Samsung TV with a motion rate of 240 will have a native refresh rate of 120 Hz.
As you can see, unless you are aware of this, it can be difficult to understand the motion rate vs the refresh rate.
There are a few different ways that TV manufacturers try and achieve smoother motion.
The most common are motion interpolation and black frame insertion/backlight scanning.
It is these processing techniques that are used to justify claims of higher refresh rates.
What Is Motion Interpolation?
The idea behind motion interpolation is that we can increase the frame rate of a video source by adding extra frames.
Frames that don’t exist in the actual recording.
Therefore, to make a 60 Hz video playback at 120 Hz (or more), we can enable motion interpolation in the display menu of the TV.
Each manufacturer will call this something different, but the idea is the same.
Motion interpolation creates extra frames by making an educated guess where the movement between two frames will go.
Effectively taking two consecutive frames and creating an extra one in the middle.
So, if the frames of a 60 Hz video go from this to this:
Then the motion interpolation will add an extra frame in the middle.
The result is the motion will look smoother because there is less of a jump from one frame to the next:
The trick to making this work effectively is how well the interpolation algorithm performs the task.
While this can work well for some fast-moving images like sports, many people don’t like it.
It can create an image that looks very unnatural – especially if used with movies. This look is often called the ‘soap opera effect’.
It is also not recommended for use with gaming as the required processing can introduce lag.
So, it is fine for watching TV shows, but it makes gaming difficult.
If you are unsure, just switch it on in the menu of your TV and see what it looks like.
You can always turn it off again!
Backlight Scanning and Black-Frame Insertion
These techniques are used on some TVs to improve motion… and also allow the manufacturer to claim a higher refresh rate.
They are not directly connected to the refresh rate of a TV, but they can be more effective on a TV with a higher 120 Hz refresh rate.
Backlight scanning and black-frame insertion are essentially the same processes. They are called different things by some manufacturers.
The idea is that by turning the screen black in between each frame of a video, we can fool the eye into seeing smoother motion.
This works because motion blur is caused in part by the pixels of the TV screen not switching color quickly enough.
With TVs, they use a process called sample and hold which results in the pixels holding on to their color for a fixed period.
The human eye can see this as a blurring of the image in fast-moving pictures.
One solution to this problem is to make the screen black in-between frames. This makes the color transition of the pixels much sharper and cleaner.
Anyway, the details on how it works are less important.
You just need to know that some people think it can be quite effective. And others can’t stand it.
These features are usually enabled and disabled in the menu settings for the TV.
Try it out and see what you think.
What Is TV Motion Blur?
I have mentioned motion blur a couple of times already, so I think it’s a good idea to explain what this is.
I think it’s important to mention this in an article on refresh rates.
Many people get confused between television refresh rates and the motion blur that they see on screen.
They assume that a high refresh rate will remove motion blur. It can help, but it’s not the solution.
Don’t forget, the frame rate of the source material is a major factor in seeing smooth motion.
Progressive video recorded at 60 fps will look smoother than that recorded at 30 fps because it captures more detail in the movement.
Motion blur is something different.
Motion blur on a TV occurs where the image appears to go blurry when there is quick movement on the screen.
This is especially noticeable with sports content.
It is a misunderstood issue because the motion blur that you see can be caused by several different factors:
- By the response time of a TV panel. Some types of TV can switch their pixels on and off faster than others. OLED TV technology has very fast response times. LED TVs less so.
- From sample and hold techniques. If the pixels are kept on for a fixed time, this can be seen to the human eye as motion blur when the picture moves quickly. Unfortunately, OLED TVs use sample and hold just as LED TVs do. So, their advantage of fast response times can be reduced.
- From blur on the source material itself. There may be motion blur fixed within the content – especially if it has been shot using low shutter speeds.
- If the image resolution has been scaled to fit the native resolution of the screen.
- From the process of deinterlacing material before displaying on a progressive TV screen.
- If the video has been compressed to help the delivery to your home e.g. online streaming services.
All of these can contribute to what people see as motion blur. As you can see, none of these are directly caused by a low refresh rate.
In a modern TV panel, there are a couple of ways to try and fix the effect of motion blur.
They are our old friends – motion interpolation and backlight scanning.
We have discussed these already further up the page.
While higher refresh rates can help to make these techniques more effective, they are just a small part of the whole problem of TV motion blur reduction.
Motion blur on a TV can be very annoying. However, some people are more sensitive to it than others.
So, what have we learned from all this technical mumbo jumbo?
Unfortunately, I’ve written a lot of words just to tell you that the refresh rate of your TV isn’t that important.
Maybe I should have just said that in the first place and saved us all a lot of time!
The main take away is that the quoted refresh rate of a TV should be taken with a pinch of salt.
If it says anything higher than 120 Hz, then that isn’t the real native refresh rate.
Even when you have the right numbers, there aren’t too many instances where the increased refresh rate will make a huge difference to your daily use.
If you like delving into the menu and changing a few settings, then you may get an improved performance in some circumstances.
However, many people don’t like the look of the processing modes that you can enable, and so don’t use them.
In many cases, you will buy a TV based on your budget.
The more expensive models will likely be 120 Hz, and the cheaper ones 60 Hz. Simple.
Just don’t get too hung up on the higher numbers.
About Home Cinema Guide
Paul started the Home Cinema Guide to help less-experienced users get the most out of today's audio-visual technology. He has worked as a sound, lighting and audio-visual engineer for around 20 years. At home, he has spent more time than is probably healthy installing, configuring, testing, de-rigging, fixing, tweaking, re-installing again (and sometimes using) various pieces of hi-fi and home cinema equipment.