Quad HD vs 1080p vs 720p comparison: here's what's the difference

You can see the maths behind this at the bottom of the article, or you can just take a look at the GIF also below that visually demonstrates how far away from a phone you need to be start noticing pixelization. Screen size and distance are in inches.

You can see the maths behind this at the bottom of the article, or you can just take a look at the GIF also below that visually demonstrates how far away from a phone you need to be start noticing pixelization. Screen size and distance are in inches." 


The new generation of Quad HD smartphones is coming. Quad HD is the common name for the new super-sharp smartphone resolution: after 720p phones’ arrival in 2011 and the jump to 1080p smartphones just last year, in 2014, we’re already bracing ourselves for the first wave of Quad HD smartphones. A few Quad HD smartphones are actually already on sale in China, but it seems that LG’s G3 will become the first truly massive smartphone with the new ultra-sharp resolution.

So what is Quad HD all about and what are the benefits it brings? As with any improvement in screen resolution, Quad HD will make smartphone screens clearer, “sharper”. The practical benefit of such a sharp display is that your eye will be able to make out the tiniest of detail in images and videos, as well as read the tiniest of fonts.

But some may ask: wasn’t that the whole point of ‘Retina’ displays way back in 2010? Hadn’t we already reached that retina-perfect picture on our devices? We’ll answer this question right away.

Screen resolution and display size: are we there yet?


Let’s first start with the iPhone 4, a smartphone that first claimed it comes with a ‘Retina’ display so sharp that the eye of a regular person no longer sees jagged pixels. The iPhone 4 was a device with a resolution of 640 x 960 pixels, but resolution alone does not tell us much about the sharpness of the display itself. After all, if you put the same resolution that looks clear on the iPhone on a 50-inch screen it would suddenly start looking not sharp at all. So instead of looking at resolution alone, it makes much more sense to look at a metric like pixel density, calculated using both screen size AND resolution.

The iPhone 4, for instance, featured pixel density of 326 pixels per inch (ppi, but some would also say dots per inch, or dpi).

Not long after, though, higher resolutions and pixel densities started to appear. Here are the pixel densities of some popular phones since then:

  • Quad HD vs 1080p vs 720p comparison: here's what's the difference
    Apple iPhone 4-5s: 326ppi
  • Samsung Galaxy S3 (4.8-inch, 720p): 306ppi
  • Samsung Galaxy S4 (5-inch, 1080p): 441ppi
  • Samsung Galaxy Note III (5.7-inch, 1080p): 386ppi

By looking at these different phones, we can again see how screens with the same resolution have different pixel densities, and thus different sharpness.

Back in the day when Apple unveiled the iPhone 4, various reports suggested that anything above roughly 300ppi is good enough for the human eye to perceive as clear and sharp. Why then screen resolutions continued growing and growing until present-day Quad HD devices?

The latest Quad HD smartphones come (or are expected to arrive) with a pixel density as high as (the seemingly unnecessary) 534ppi! Is it really just new technology for nothing?

The third factor: viewing distance


There is another key factor that should be considered when we speak about display sharpness and clarity, though, but it’s often left out of the conversation. We’re speaking about viewing distance. Even the sharpest of TVs and the sharpest of phones starts to look flawed when you look at it from a very close distance. Look at the same device from a 1-foot distance and the clarity of the picture suddenly becomes better. Look at it from further away, and the picture would appear perfectly sharp and clear.

The question that we will answer today then is: at what viewing distance one starts actually seeing the benefit of high-res displays?

The ideal viewing distance


To measure the ideal distance between you and your smartphone display, we’ll assume you are one of the rare few who have very good vision. You’d often hear about such vision being called 20/20 vision. A person with 20/20 vision is one who can discern detail of 1 arc minute (1 arc minute = 1/60 of a degree = a circle has 360 degrees, so 1 arc minute = 1/21600th of a full circle). Most people have worse vision than that - for instance someone with 20/40 vision can only discern detail of 2 arc minutes, while the rear few (think jet pilots) with 20/10 vision can discern detail of 0.5 arc minutes. The actual limit of human vision is around 20/8, so again, we’re assuming a fairly optimistic 20/20 vision scenario.

So with all that in mind, how close do you need to be start seeing those pixels and details on even a Quad HD smartphone? And what about 1080p phones, and 720p devices? Take a look below:

  • Typical 480p phone (4” display like Galaxy S III Mini): eye starts to notice pixelization from 14.73” (37.4cm)
  • Typical 720p phone (4.7” display like Nexus 4): eye starts to notice pixelization from 11” (28cm)
  • Typical 1080p phone (5” display like Galaxy S5): eye starts to notice pixelization from 7.8” (19.8cm)
  • Typical 1440p phone (5.5” display like expected LG G3): eye starts to notice pixelization from 6.44” (16.4cm)

480p, average person starts noticing pixelization at around 14.7 inches (here - 37.4cm) in a 4-inch 480p phone
720p, average person starts noticing pixelization at around 11 inches in a 4.7-inch 720p phone
1080p, average person starts noticing pixelization at around 7.8 inches in a 5-inch 1080p phone
Quad HD, average person starts noticing pixelization at around 6.44 inches in a 5.5-inch 1440p phone
We've used a ruler with metric units (centimeters, rather than inches)

We've used a ruler with metric units (centimeters, rather than inches)

*we’ve used the following formulas to calculate those distances:
VIEWING DISTANCE = 1 / PPI / (2 * Tan (VISUAL RESOLUTION / 2))
PPI = X / sqrt (W ^ 2 / ((Y / X) ^ 2 + 1))), where x = horizontal resolution, y = vertical resolution, w = screen size
VISUAL RESOLUTION = (1 / VISUAL ACCUITY) * (1 / 60)
We’ve assumed 20/20 VISUAL ACCUITY

Conclusion


In conclusion, we ought to put a few disclaimers to all this. We've tried to keep it as scientifically accurate as possible, but we ought to remember that our eyes and our human vision is more complex and the actual way we see things is a lot about how the brain processes images. And that's something that is hard to measure right now.

With this in mind, we'll lay it out in very simple terms: theoretically, you need to look at your 5.5-inch Quad HD from as close as 6.4" for your eyes to start noticing pixelization (if you have 20/20 vision, if not you'd need it even close). At regular viewing distances it's practically impossible to notice the difference in sharpness between say the 1080p Galaxy S5 and the future Quad HD flagships.

Not very encouraging, is it? We, however, can still hope that theory is not all to it, and will put it all to the test very soon as the first Quad HD phones are expected to hit the market in the coming months. Stay tuned!

reference: Carlton Bale, jaredjared.com
Second image is courtesy of CNET.

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107 Comments

1. StraightEdgeNexus

Posts: 3689; Member since: Feb 14, 2014

I cant see the difference :-( ................

15. Ashoaib

Posts: 3238; Member since: Nov 15, 2013

Well, I always felt the difference with jump in display resolution

45. proto

Posts: 59; Member since: Sep 12, 2012

well, when i replace galaxy nexus (4,65" 720p) with Galaxy S4 (5" 1080p) it was realy hard to find difference even side by side from normal veawing distance, I had to go to "recent apps" menu to finally see some differnece. No needto say theat both have pentile pixell arrangement.

52. kshell1

Posts: 1143; Member since: Oct 05, 2011

I jumped from 480p on 4.3" with a Droid X, to 720p on 4.5" on my Moto G, there is a massive difference.

63. Nikolas.Oliver

Posts: 1574; Member since: Jul 01, 2012

Hey you stole my my display picture

79. Epicness1o1

Posts: 298; Member since: May 30, 2013

I jumped many times when I was playing basketball ^^

99. JC557

Posts: 1913; Member since: Dec 07, 2011

I compared the display of my LG Spectrum 2 & Moto X (4.7" @ 720) to that of my sister's HTC One M7 (4.7" @ 1080) and my M8 (okay different display size but hey) and found that at 1080 words on webpages were clearer and also allowed a bit more on screen. I also found that I had to move the phone further away from my face when it came to the higher resolution. QHD... maybe there'll be benefits like in media viewing but I'd have to see it in person first. There's no question though, I cannot go back to the qHD display on my Droid Razr M... it's usable but not preferable at this point.

61. joey_sfb

Posts: 6794; Member since: Mar 29, 2012

Looking at 60 TV, Full HD look quite pixilated compare to UHD or 4K. For phone less than 5 inch 720p or HD should suffice. That been said I will still pick the highest possible resolution available. Does not make sense to go backward as high resolution screen also mean higher specification is put in to support the screen.

81. DanishDynamite

Posts: 47; Member since: Feb 28, 2013

UHD is 4K...

95. chebner

Posts: 249; Member since: Oct 17, 2011

UltraHD and 4K are used interchangeably, but technically they are different. True 4K, used in digital cinema, is 4096 × 2160. Ultra HD, used in TVs is 3840 x 2160. UHD is more suitable for TVs because it is exactly (1920*2) x (1080*2) which makes scaling 1080p with minimal scaling artifacts much simpler.

50. akki20892

Posts: 3902; Member since: Feb 04, 2013

Don't try to judge me..... http://www.jigsawexplorer.com/puzzles/subjects/eye-of-the-eagle-344x300.jpg I'm sure this buddy can notice pixels really well. This buddy need 5" with 1,000,000K.

56. rd_nest

Posts: 1656; Member since: Jun 06, 2010

That formula they used is slightly wrong. PA mentioned: VIEWING DISTANCE = 1 / PPI / (2 * Tan (VISUAL RESOLUTION / 2)) Instead it should be: VIEWING DISTANCE = 1 / PPI * (2 * Tan (VISUAL RESOLUTION / 2)) Just an example (for 480p 4-inch display, PPI of 233.24) -- VIEWING DISTANCE = 1 / PPI * (2 * Tan (VISUAL RESOLUTION / 2)) = 1 / 233.24 * (2 * Tan [1/120] ) = 14.74 inch

72. givemespecs unregistered

Boooorrriiiinnnggggg

76. KDNISS

Posts: 4; Member since: May 12, 2014

Stupid people do not understand the Math :)

92. AfterShock

Posts: 4146; Member since: Nov 02, 2012

4 out of 3 people struggle with math.

97. zunaidahmed

Posts: 1182; Member since: Dec 24, 2011

I guess u r struggling..... 4 out of 3, it should be 3 out of 4......lol

98. ardent1

Posts: 2000; Member since: Apr 16, 2011

You missed the sacrcasm. Lol

106. iampayne

Posts: 322; Member since: Aug 12, 2013

The Joke _________ Your Head

107. TheOldOne

Posts: 196; Member since: Mar 29, 2012

thank you good sir for pointing this out. I still don't understand why they keep mentioning "screen size"... the relevant paramter here is the PPI/DPI not the screen size! But I guess is in the way the devices are advertized today, they only talk abour "screen size" and "resolution" and not emphasizing enough in how "fine" the display is.

64. jcdz89

Posts: 78; Member since: Mar 01, 2013

1080p enough for phones.. 1440p enough for large tab. .that's it

84. latido

Posts: 45; Member since: May 31, 2012

IMO, I see the different when playing HD games.. on SGS3 720p, the games look very sharp. but on note3 1080P, the games graphic look softer.

88. Kamehameha

Posts: 44; Member since: Apr 21, 2014

"on SGS3 720p, the games look very sharp. but on note3 1080P, the games graphic look softer" Pics or it didn't happen.

89. mmmanuuu

Posts: 403; Member since: Nov 05, 2013

Dear phone arena why are you flooding your site by posting the same article again and again???

94. Neo_Huang

Posts: 1067; Member since: Dec 06, 2013

I think they replaced Oppo Find 7 with LG G3 as the example of a 2K phone.

101. radex

Posts: 7; Member since: May 30, 2014

from 720p and on ... neither can I

3. Antimio

Posts: 313; Member since: Nov 11, 2013

Amazing explanation. Thank you Guys for taking your time. Honestly, I don't mind having a 720p or 1080p. Nexus 4 and Moto X here, and pretty happy with them.

20. KillgoreTroutTime

Posts: 433; Member since: Jan 06, 2014

Iv'e got a Moto X and I swear the display looks much nicer than the LG G2 I had before it. I don't think my eyes really care about the difference between 720 and 1080

90. Kamehameha

Posts: 44; Member since: Apr 21, 2014

You should be happy. You have the eyes of a normal human, not an eagle.

4. MalakiMills

Posts: 257; Member since: Jun 15, 2010

I think 1080p is the sweet spot for smart phone displays right. I generally stay away from the idea that there is a "cap" on any sort of advancement, and I do think displays can still be improved upon. Resolution however is good where it is. I'd rather see things like battery, graphics, camera, and software optimizations continue to be pushed ahead with priority over displays.

21. KillgoreTroutTime

Posts: 433; Member since: Jan 06, 2014

There is a cap. The human body can only experience things to a certain level. We have already reached the cap for music quality regardless of what supporters of pseudoscience have to say about it. We could make phones emit in infrared and ultra violet, but it is not like it would be noticeable to us.

* Some comments have been hidden, because they don't meet the discussions rules.

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