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Page 1 of 1: HDTV Viewing Distance Calculator + Guide
A report recently showed that 30% of US homes now have an HDTV. And this number is likely to grow even further now that analog transmissions will be ending around the world over the next few years, and Blu-ray and HD cable adoption increases. There is one question though that people often ask when buying a HDTV - how far should I sit from it?
What seems like an easy question to answer is actually quite complicated. Factors such as eye sight, the TV's resolution and size, are all factors. This guide aims to provide you with some tips that will help you choose the right viewing distance for your TV, and the opposite too of choosing the right TV for your viewing position.
The Science of Viewing Distances
Viewing distance can seriously affect the enjoyment of HD content on HDTVs. Too close, and while you're seeing all the detail, it would be akin to sitting at the front row at the cinemas. Sit too far away, and you miss all the details, and you negate the whole point of purchasing a large screen HDTV. The ideal viewing distance would be one where you are able to see all the details, but is also as far away as possible from the TV - this is the number (in feet or meters) that this guide will provide you.
The factors which affect viewing distances include:
- The type of TV (LCD, Plasma, CRT, Projection ...)
- The size of the TV
- The resolution of the TV
- The resolution of the content you are watching on the TV
- The viewer's eyesight
- The comfort of the viewer
This guide will simplify the equations involved by assuming a few things, and ignoring others (Chapter 3 of the lazy article writer's guide). The type of TV will be assumed to be LCD (and variants, such as LED) or plasma, as these are the most common on the market. They also use finite number of pixels, which make calculations easier. By assuming LCD or plasma, this also allows the resolution of the content to be discounted (not really, but read on ...), as these TVs scale everything to their native resolution (based on the number of finite pixels each TV has). The reason why you cannot actually discount the resolution of the content is that, as anyone knows, watching a VHS recording will not be the same as watching a Blu-ray movie, even if the VHS signal has been upscaled to Blu-ray resolution. On the other hand, 1080p content downscaled to 720p and displayed on a 720p TV will look the same (if not better) than native 720p content. For the purpose of this guide, we're going to assume the content is fed to the TV at the TV's native resolution or is being downscaled (so 1080p downscaled or 720p for a 720p TV, 1080p for a 1080p TV, and so on) - if you're worried about viewing distances, then the least you could do is to provide suitable content for your TV, as opposed to VHS recordings.
The viewer's eyesight will of course determine how much detail you can see from what distances. Again, for calculations to be meaningful but not bogged down in detail, it has to be assumed that the viewer's eyesight is near perfect.
The comfort factor is the most subjective of all. While one person may feel comfortable sitting only 5 feet/1.5m from a 50" TV, another person may find it too close. This is something that you, as the viewer, will have to find out for yourselves. This guide can only provide you with the optimal viewing distance based on perception of detail, as opposed to how each person feels about how far they want to sit away from the TV. With this said though, it is my personal experience that what may seem too large at first, will not over time - and as long as you're not actually feeling physical discomfort (dizzy, nauseous), then the TV will feel smaller and smaller until one day you decide it's too small.
So to sum up, the calculator below will give you the optimal viewing distance based on the size and resolution of your TV, while assuming the viewer has perfect eyesight while viewing a LCD or plasma TV (or any display with fixed number of pixels), watching content native or downscaled to the resolution of the TV.
The Calculator
I have built a simple calculator that given the resolution of the TV and the size of the TV, the viewing distance will be calculated and shown in feet and meters. There is a pre-filled list of common HDTV resolutions, or you can select the "Custom" option and enter your own resolution. The methodology used in this calculator is based on the one used by this forum thread on AV Forums, although slightly simplified for easier (digital) digestion. And that methodology is based on the theory regarding the resolving power of the eye being 1 minute of Arc, or 1/60 of a degree. This then allows the distance from which the eye is no longer able to distinguish detail based on the size of the TV's pixels. This is only one theory of viewing distances, and there are more complicated methods, including even a THX recommended method which you will find here. But if you want a quick and dirty viewing distance, then here it is below.
If you cannot see the calculator above, you can access the calculator here instead.
Now that you've got your number in feet or meters, it is important to note that this is just a scientific calculation of the "ideal" viewing distance. You should only use this as a guide, and it is very likely that you may find this number to be too close or too far, depending on your personal preference. What this number does tell you is that, if you go further than this distance, then you will be unlikely to perceive all the details in the picture. According to the THX formula, you should try to sit closer than the number displayed above. So if your actual viewing distance is already further way than this number, then you should consider sitting closer to the TV, or getting a bigger one. But as noted above, personal preference comes into play and if you're the type to get car sick easily, then you should not move too much closer than the calculated number.
As a personal example, I have a 1280x720 (720p) 50" TV and I sit around 2 to 2.5 meters away. My eyesight is far from perfect, but watching TV is comfortable for me (despite me being prone to car sickness). According to the calculator above, the "ideal" distance for me is 2.97 meters away, but given my less than perfect eyesight, 2 to 2.5m should give me the same effect. Any closer, and I think I would be uncomfortable, and any further way, then I won't be able to see a lot of details in a typical 720p transmission.
More confused than when you started? Hopefully that's not the case. In any case, viewing distance is as important as choosing the size or resolution of your TV (because all three are related), and so the next time you buy an HDTV, please take into consideration the viewing distance as well.
Got a questions about this guide or about HDTV in general? Post them in our HDTV forum and get them answered by myself or other expert users.
