Lechner Distance: The Number You Need to Know Before Buying an HDTV

December 4th, 2006 · 32 Comments · Reference Materials

Bernard Lechner is an award winning television engineer. At RCA he was heavily involved in the development of HDTV. Lechner researched the typical distance between a viewer and their television screen by taking measurements in many American homes. The median distance complied from all his data came out to 9 feet. This measurement is now called the Lechner distance.

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Your viewing distance based on Lechner’s analysis is very likely to be 9 feet. There are two standard HD broadcast resolutions 720 lines and 1080 lines. The following are the minimum screen sizes that will let your eyes resolve all the detail at the Lechner distance, one for each HD broadcast resolution.

For a 720p display it’s a 46″ screen size.
For 1080i or 1080p display it”s a whopping 69″ screen. All screen measurements are diagonal inches.

A smaller display for each given resolution will not allow your eyes to perceive all the detail that appears in HDTV.

For the  maximum viewing distances for different screen sizes see my exclusive Viewing Distance Chart at

http://hdguru.com/wp-content/uploads/2006/11/hdtv_distance_chart.pdf

 

Copyright 2006 HD Guru Inc. All rights reserved. HD Guru is a registered trademark

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32 Comments so far ↓

  • daarrid

    Once again the HD Guru confuses the ability of the eye to distingush each and every pixel as a basis for recommending screen size.

    Sadly no one receives anything close to accurate pixel to pixel information on their HDTVs. All video, including high definition, is compressed and that means any number of pixels are averaged and no where near totally accurate.

    Angle of view, as suggested by STME and THX is a better gauge of how involved you will be in a cinema like experience.

  • Wayne

    The narrative lead-in preceding the link to the website chart says the chart specifies “MAXIMUM” viewing distance, but the chart column label is ” OPTIMUM” distance. I’d like to see BOTH….

    They are the same. The 1080i/p distance for a given screen size is the maximum distance from the screen where person can perceive all the resolution in the picture. If you move between the 1080p and 720p distance the 1080p image will be sharper. When you reach the 720p distance and beyond for a given screen size you will not be able to perceive the higher sharpness of the 1080p display over the 720p display because you are to far away from the screen for your eyes to resolve the 1080p screens higher resolution.

    HD Guru

  • ExSophus

    A few things I do have to complain about because they do affect the practical value of the data you are providing…

    Providing the “distance” data out to 2 decimal places is MEANINGLESS. It just clutters the table and needlessly makes it more difficult to interpret.

    Rounding distance results to the nearest inch, and the “diagonal” to the nearest 0.5″ is sufficient. Adding more decimal places just makes it less useful.

    Similarly, providing the height and width values is redundant. You have already provided the most often specified physical screen attribute, the “diagonal”, and you specified the aspect ratios…so the H&Ws are redundant and again…that clutters up the table and needlessly makes it more difficult for people to follow the rows/columns and actually use the results.

    Lastly, you might consider adding a reminder to people to be sure the vendor’s specified “diagonal” is the maximum image diagonal…and not just the physical diagonal. For example, I’ve seen a disreputable vendor try to sell a 24″ image capable TV as a 28″ TV by using a tape measure to “prove” to them it measures 28″ from corner to corner of the exterior of the TV head. They tried to tell the customer it was mis-marked on the tag so they were “actually” getting a 28″ display for the price of a 24″ display…what a super deal!

  • ExSophus

    I don’t believe it was intended or included in the assessment, but HDguru’s “exclusive Viewing Distance Chart” in addition to addressing the resolution issue, also appears to show viewing distances that mitigate the problems some LCD technologies have with limited viewing angles.

    Sitting farther back, while remaining at the same horizontal and/or vertical position relative to the screen, reduces the sometimes very obvious color, contrast, and brightness shifting that can often destroy a viewing experience on those screens with more limited viewing angles. This is because as you move back the absolute offset angle at which you were viewing portions of the screen decreases.

  • Steven Conner

    In college, second Art class–major is CIS; however, wanted to add this, which is neat: Pointillism in art, by Seurat, painted dot by dot, to show that visual capacity is truly an illusion–this he was trying to force the viewers optics to “create” the color rather than the painting, thus the painter–to create the color for the viewer–the problem to be discoverd is that his pointiism art is only viewable at certain distances, beyond six feet (I think), his art becomes blurred and the colors turn to brown hues.

    –this is where optical colors come into play, such as bluegreen or is it red/green as a primary color since if one stares at primary charted/segmented color then looks away at a white sheet their eyes “create” the primary/secondary color automatically from the previous color. Neat huh? :)

    –now if we had the optics of the sea http://www.livescience.com/technology/091025-mantis-shrimp-eyes.html

    –this could explain why colors/objects bend before our eyes, columns from far away (entasis), or similiar illusions–like staring at a chair leg through a chairs enclosed arm–the leg becomes distorted in the optics–probably new color is happening here and our eyes cannot handle it(refraction of light too), so the consequence is bluring.

    So in essence, feet and distance to matter espeically if one wants to spend bundles on networking and video elements–understanding the aggregate is essential.

  • Nick

    So if I have 20/14 vision I could sit further away than the recommendations, right? Also, the average person actually has vision superior to 20/16, so most people could sit further away (or use a smaller screen)

    (For those who don’t know, 20/16 is better than 20/20 for seeing at a distance)

  • Mort

    I think someone wanted some equations… well, here they are:
    I – screen diagonal in inches
    D – optimum viewing distance, also in inches

    for 16:9, 1080i/p:
    D = 1.568 * I

    for 16:9, 720p:
    D = 2.352 * I

  • Mike Liveright

    I’d like an equation, or set of equations, that is derived. that says something like:

    1080 set “I” inches, sit “F” feet,

    ~ F = I/7.6 (1080)

    720 screen I” inches sit “F” feed,

    ~ F = I/5.1 (720)

    16*9 screen

    ~ Width = 87%*I, (16*9 diag)

    4×3 screen

    ~ Width = 80%*I (4*3 diag)

    16*9 high definition screen diagonal “HD” whose picture is the same height as 4*3 standard definition’s screen’s diagonal “SD”,

    ~ HD = 122%*SD

    ==============================

  • Kerry

    I’m sitting at somewhere in the neighborhood of 12 feet or 144 inches. I’m looking at the Sharp LC-52D64U. Do you think it would work?

  • Bob

    Guru,

    I am purchasing an HDTV for our bedroom and will watch lots of sports. We are 140″ from the tv when in bed. Our space will not accomodate larger than a 40″. What is your recommendation on screen size and pixel resolution?

  • Jeff Paul

    This blog Is very informative , I am really pleased to post my comment on this blog . It helped me with ocean of knowledge so I really belive you will do much better in the future . Good job web master .

  • Bob Stone

    I’ll confess to being confused regarding HDTV formats. I remember in an earlier HD GURU Basics article that there were just two high definition formats – 720p and 1080i. I was surprised to read in this discussion that a 1080p format exists and my HDTV tuner can receive it.

    This whole issue cries out for more clarity. I wonder if the HDGURU would publish a chart showing all the formats as they exist on paper, what formats are currently in use and by who (be it — broadcast TV, cable, satellite, or Blueray disc).

  • Terry

    What viewing distance is the minimum for viewing 3d movies on my tv that is 3d ready. I have the media to support this technology.

  • TIM

    DOES THE TYPE OF HDTV MAKE A DIFFERENCE IN THE OPTIMUM VIEWING DISTANCE EG FRONT VS REAR PROJECTION…PLASMA VS LCD ETC

    NO. Of course sitting close to an LCD will reveal more of the motion artifacts the technology creates

    The HD Guru

  • Craig

    I have a 62″ rear projection HD TV with comcast digital HD cable box. I have noticed I rarely receive a broadcast higher than 720p, even tho Im supposed to receive shows in 1080. Is this because the shows are not braoadcast in 1080 or could it be something is not hooked up or dialed in correctly on my system. Also prior to purchase of HD TV , a comcast tech showed me a way to change the settings on the cablebox to receive 1080 but I didnt pay attention because I didnt own an HDTV at the time. Could this be my problem? Thanks in advance

    Check with you cable provider for instructions to change the output setting on the cable box to 1080i (each  brand box is uses a different method)

    The HD Guru 

  • erika

    Does the Samsung LN-S4696 or the Sony KDL46XBR3 have built-in HD tuner? If not does any 46″ 1080p tv have build-in HD tuners?

     Both sets have built-in HDTV tuners

    The HD Guru 

  • Rick

    Thanks guru for the great info, plus viewer’s responses. All very helpful.

    My question… as 3D movies are making a slow entry back into our theatres and homes… I have heard LCD is the best way to go. I have heard you cannot view 3D on a plasma or DLP. Not sure if that is correct??? Any info for dispelling ‘truth?’

    Star Wars is being 3D’d

    The Polar Express – by far the best 3D movie… ever. Little retinal rivalry.

    That DEEP SEA-3D IMAX movie was horrible. Went cross-eyed viewing that movie.

    RMad

    A number of CE companies are working on 3D TV without glasss (The HG Guru prefers the term Stereoscopic TV) I have seen demonstrations of Philips’ Stereoscopic commercial display. I expect a number of new demos at the 2007 CES in January. The HD Guru will report on any models planned for US introduction. I know of no limitation for “3D” on different display technoliges using glasses.

    The HD Guru 

  • Brian

    Can you tell me the maximum resolution the S-Video will transmit. I want to replace my DVD but would like to use S-Video to connect will i be wasting my time and money on a progressive scan DVD player?

    S-Video is an analog connection vs. a HDMI a digital connection. Digital is better. Anyway it is rated in horizontal lines at around 400. S-Video is not compatible with any type of signal other than 480i, so yes if you plan to buy a progressive player an connect it with S-video you will wasting your money. The connections from best to worse are 

    HDMI (or DVI same video signal);component video ; S-video ;composite video

    Only HDMI/DVI and component video canallow the transfer of a signal above 480i (480p, 720p, 1080i/p)

    The HD Guru 

  • Dave

    I sell TV’s (Pioneer Elite, Marantz, Fujitsu, Director Series Hitachi and other premium HD TV’s) to peddle my way through school. I was very excited to find material on a reputable website to back my claims against the immidiate necessity of 1080p, high contrast ratios (do you agree the human eye can only see 300:1?), and refresh rates–to name a few. For that, I thank you. I think it’s sad that most retailers will jump on the numbers game and use the hype to sell the customer rather than what’s really behind the numbers. My questions to you are these; when do you think 1080p will actually be a broadcast? Will the technology change so much by that point that 1080p TV’s sold now won’t be compatible? Why would 1080P be such an issue when there’s hardly any 720P or 1080i being broadcast? There is so much mis-information on the internet it’s hard for the average consumer–especially if they haven’t purchased a TV in the past 10-15 years–to even know where to begin. This website is very straight foward and non-objective from what I’ve read so far. I’ve actually been referring customers who are new in the market to this website to help them make better informed descisions–especially when it comes to the amount of money some of them put into their systems!
    One last thing, I read in one of the articles that it’s recommended for the customer to bring a DVD into the store as well as a player if necessary to test the refresh rate of the TV. Well that’s good advice I would also like to add that asking the sales associate to change the channel to a basic analog channel. In my area it’s news channel 3 that’s the worse reception that I can turn the TV to. Why? 1080P or I Tv’s have to show that resolution no matter what the source. When you look at a wall of HD Tv’s all on the HD source, it’s very hard to pick a difference from one to the other except for maybe color schemes–which most can be adjusted to your liking. What you see on an analog channel–not a DVD–is the scaler on the TV (or analog processor) going to work to make the picture the highest resolution. Most of what you watch regardless of whether or not you have blu-ray and an HD package through your providor is still analog–or 480i. The TV looks great in the store, but will look vastly different over your fire place when it’s showing a non-HD picture. The quality of the TV’s will jump out at you when they’re all showing regular 480i and this could help make the decision making process easier for you!

    Good suggestions. Latest information, it will be years, I will guess 4-5 before the existing HD networks will switch over to 1080p. Tons of money has already been spend on 720p and 1080i and this equpment must be ready for replacement before I see changing the entire chain (cameras, switchers ,character generators and so on.)  from one format to the other . Perhaps a future new HD network will jump in first.

    The good news no one talks about is: all built-in and external HD tuners will accept any of the 18 ATSC standard formats (9 are HD) and convert the signal to what your TV accepts, so it will never go black or become obselete if a network changes over or a new 1080p network appears. The 1080p broadcast formats  are 24 frames per second and 30 fps, so either one would have to be upconverted to at least 60fps (or else the image would flicker) The built- in digtial TV tuners in 1080p displays  “1080p broadcast ready” today

    The HD Guru 

  • Greg

    I’m finding your whole site rather informative. We’re remodeling our house to include a 23′ x 35′ Great Room, where we want to incorporate a nice HD system. Your site is full of useful information that I’ve found quite helpful in deciding which direction I should take in choosing a system. When the remodeling is at the “finishing” stage, I’ll be sure to check back in to get the latest updates you have to offer.

    One recommendation: Referring to yourself in the third-person is disturbing. If you are more than one person gathering this info, conducting these tests & posting these findings, perhaps you should consider re-naming yourselves the HD Gurus.

    That’s what Greg thinks. Greg things you have a great site, but Greg thinks you should stop with the third person narration.

    Press on!

  • jesus

    holy crap… i sell hd tvs all day and you people… customers and this website included are all idiots… i don’t even work on comission and i can dispell so many rumors about crappy tvs. you sicken me go to hell!

  • Carl Taylor

    Does this sound right. After finding the correct technology of choice, with the best resolution at the right distance, it all doesn’t count for much if the broadcaster uses a low bit rate. Both analog and especially HD video will suffer, correct?

    Just digital. But you will be able to see the finest HD available if you get an HD DVD or Blu-ray player and HD broadcasts may better down the road.

    The HD Guru 

  • Ben

    What happens if you sit closer than the specified distance? For example, the distance for a 69″ diagonal screen with 1080 resolution is 108.26″. Is there anything wrong with sitting at 96″ or 84″? Are there some factors that result in a minimal acceptable viewing distance?

    Sit too close and you may begin notice the pixel grid structure. Look and measure before buying and you will be fine 

    The HD Guru 

  • Geoff

    Never mind…figured it out. Under the “720P Optimum viewing distance” column, I searched for the number closest to 108 and saw where “16X9 diagonal” =46. Same thing for the “1080I/P Optimum viewing distance” column. I searched for the number closest to 108 and saw where “16X9 diagonal” =69.

    This is a great chart, but a few recommendations:
    1) Spell check all words including “diagional”
    2) Is there a way to highlight the two optimum viewing distance rows for both the 720P and 1080I/P?

    ——————————————————————-

    Sorry about the spelling. Revising the chart to make easier to read is on the HD Guru to do list, it will soon along with other planned improvements as we begin the new year.

    The HD Guru 

     

  • John Cassino

    is the Sony KDL 46V25L1 up for review?

  • Geoff

    Please provide clarification on how to interpret the data in the Viewing Distance Chart.

    The viewing distance chart is caculated based upon human visual acuity proving the maxium viewing distance a person with 20/20 vision (or corrected to 20/20) can see all the detail displayed  on a 720 HDTV and a 1080 line (i or p) HDTV .

    Most of the charts I have seen in so called “hd guides”  generally list a single distance for a given screen size that is too far  to see all the fine detail within HD content.

    The average distance as seen in the Lechner article is 9 feet. 

    You can view beyond the maximum distance but you will not be perceiving all the detail within the image. 

    My advice  : to fully experience HDTV buy a large enough screen for your viewing distance.

     The HD Guru

  • Danel

    I was looking over the numbers that you put together for viewing Distance. I am still a little confused. I have a 16 distance from the couch to the HDTV entertainment Center. When I made the built in I designed it for a 42 to 46 inch screen because the data at the time told me that would be the best viewing area for that size screen. what will I loose if I put a Plasma in vs a LCD . what size do you think I should put in that area. I have also been looking at projection system also but I don’t want to pull a sreen down every time I use it. I have also been told that they are still not a good way to watch TV still; is that true.

    Thanks

    Daniel

  • Gary

    Guru:

    Nevermind. I went to check out the 50″ Vizio next to Hitachi & Panosonic Plasmas. There was no comparison. Vizio wasn’t even in the same universe as other plasmas. My personal opinion is for LCD. To me they are crisper than Plasmas side by side. The Bravia XBR2 & 3 are the best out there. Only thing is I heard about a “clouding” problem with these sets. Any light on this subject? I heard Sony say’s it’s normal? People that have bought them are really mad at Sony, others don’t have the problem at all.

    Thanks Guru you sight is very helpful!

  • Gary

    Guru:

    Do you feel the 50″ Vizo Plasma you tested has the same technology to prevent burn-in, and have the longevity as other plasmas?

    Thank,
    Gary

  • Gary

    HD Guru:

    If 46″ TV’s are better in 720p then why is every company making them in 1080p? Did I mis-read your comment about 1080p for 46″. I noticed you have not commented on the new Sony 46″ Bravia XBR3 LCD. Any experience with this TV?

    Thanks,
    Gary

    —————————————————————————————–

    My point, a 1080p display requires better,  powerful signal processing, to maintain good image quality of non-HD source material. If a vendor uses a 1080p panel but does not incorperate the best signal processing, the standard def stuff will  probably look inferior than the same material displayed on a 720p set. Bottom line, if you are going to watch SD material on a 1080p set, it needs to have a good processor. Some of the major vendors have overall consistantly better signal processing across the board, others only have it in top-of-the-line models, , while some have poor processing in all models. Check out product reviews and my tests of deinterlacing and 3:2, if the processor doesn’t do that well it may not do a very good job with standard def signals.

     The HD Guru

  • Marvin

    Viewing a screen from beyond the optimal viewing distance will prevent you from appreciating ALL the available detail of 1080p, but will the increased resolution still have SOME advantage compared to a 720p set at the same distance?

    Thanks,
    Marvin

    ———————————————————————————————————-

    Yes , the 1080p will look better but as you move toward the 720p distance and beyond degree of differentiation dimishes..

    The HD Guru 

     

     

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