New iMac Display Sizes

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Level 1

140 points

New iMac Display Sizes

I'm ready to buy one of the new iMac models but when looking at the current 20", 24" monitors, I think the 24" is the largest I can comfortable accommodate on my desk.

I note that the newly released iMac is available as a 21.5" or a 27" in a 16:9 ratio. What was the old ratio, or better yet, is the viewable screen size of a new 27" the same as the old 24" or is it larger?

If the new sizes equal the viewable sizes of the old iMac screens then I can accommodate a 27" model on my desk. If it is larger, I'll have to get a 21.5".

Thanks

kayjh

15" MacBook Pro, 3GB RAM, 160GB HDD 7200 (20" iMac G5. 1.5GB RAM, 500GB HDD/60 GB Video iPod)

Posted on Oct 20, 2009 10:06 AM

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Answer 1

Dah•veed

Level 9

64,645 points

Oct 20, 2009 11:09 AM in response to kayjh

The new Macs are larger. Display sizes are measured diagonally, from like the bottom left corner to the top right corner. So the new 21.5" is 1.5" larger than the 20" diagonally, the 27" is 3" larger diagonally than the 24".

Dah•veed

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Answer 2

kayjh Author

Level 1

140 points

Oct 20, 2009 11:17 AM in response to Dah•veed

Thanks for the reply David. The reason I asked the question is that Apple is advertising the new screen as a true 16:9 HD format as opposed to the old format (which was what aspect ratio?).

It got me thinking that this might not be a true screen size increase as the aspect ration may have changed. For example, a 20" 4:3 aspect ratio screen would be larger than a 20" 16:9 aspect ratio screen, so if the old aspect ratio was for example 15:7 (at 24"), the 27" screen at 16:9 wouldn't be a true 3 inches larger.

Do you know what the old aspect ratio was??

kayjh

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Answer 3

Kalagan

Level 2

257 points

Oct 20, 2009 11:41 AM in response to kayjh

Hi,

The OLD aspect ration was 16x10, 1920x1200, not 1920x1080. the extra 120 Pixels was the height of the top menu bar. Apple did it that way so you could display a full HD 1920x1080 image and still have the menu up there.

The menu bar can now be transparent, so I guess Apple figured that the extra 120 pixels weren't necessary.

So, in short, it use to be 16x10 now they have gone to a true 16x9 aspect ratio.

Kalagan

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Answer 4

kayjh Author

Level 1

140 points

Oct 20, 2009 12:55 PM in response to Kalagan

Kalagan,

So that means that the new 27" display is larger than the 24" (in terms of viewable area), but the viewable area doesn't increase by the full 3" because part of it is taken up by a slight change in aspect ratio.

I guess I'll have to head down to the Apple store to compare.

On my home office desk, I think I'll have about an arm's length from my face to the front of the monitor. I wonder what is the typical comfortable distance for a monitor of this size.

kayjh

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Answer 5

Dah•veed

Level 9

64,645 points

Oct 20, 2009 1:06 PM in response to kayjh

I think that you are playing a math game with screen resolutions that Apple does not play. When Apple says that a display is 17" diagonally it is 17" diagonally. I have a 17" iMac and the display is exactly 17". The full computer is a bit larger still.

Dah•veed

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Answer 6

Oct 20, 2009 2:41 PM in response to kayjh

The important numbers are resolution numbers, not the diagonal size number.

The new 27-inch display is 2560x1440. The old 24-inch display was 1920x1200. Both numbers on the new display are larger. That means that ALL the pixel from the old display will fit within the new display. You could open a window that is the full size of the 24-inch iMac's display, and it will completely fit on a 27-inch display with room to space.

So the new display is obviously "larger," both in physical size and pixel count. If you go by pixel count, the old one has 2304000 (1920x1200). The new one has 3686400 (2560x1440). That's a 60% increase in screen real estate, based on number of pixels.

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Answer 7

kayjh Author

Level 1

140 points

Oct 20, 2009 6:59 PM in response to Kenichi Watanabe

But it doesn't tell you physically how much bigger the display is. It could mean denser pixels for higher resolution couldn't it? Obviously the 27" screen is going to have more real estate, the question is exactly how much more? I guess I'll have to wait and compare. 🙂

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Answer 8

Dah•veed

Level 9

64,645 points

Oct 20, 2009 7:16 PM in response to kayjh

The stated dimensions for the new Macs are;
21.5-inch iMac
Height:
17.75 inches (45.1 cm)
Width:
20.8 inches (52.8 cm)
Depth:
7.42 inches (18.85 cm)
Weight:
20.5 pounds (9.3 kg)

27-inch iMac
Height:
20.4 inches (51.7 cm)
Width:
25.6 inches (65 cm)
Depth:
8.15 inches (20.7 cm)
Weight:
20 pounds (13.8 kg)

The older ones are;

20 inch iMac
Height:
18.5 inches (46.9 cm)
Width:
19.1 inches (48.5 cm)
Depth:
7.4 inches (18.9 cm)
Weight:
20 pounds (9.1 kg)

24" iMac
Height:
20.5 inches (52 cm)
Width:
22.4 inches (56.9 cm)
Depth:
8.1 inches (20.7 cm)
Weight:
20.5 pounds (11.5 kg)

Dah•veed

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Answer 9

Oct 20, 2009 8:07 PM in response to kayjh

Again, the important thing is pixel count. A 50-inch HDTV may have a physically larger display, but it only has 1920x1080 pixels (the same as the 21.5-inch new iMac). Larger pixels does not let you do more with your computer, MORE pixels does.

You can figure out the pixel density this way. Using the [Pythagorean theorem|http://en.wikipedia.org/wiki/Pythagorean_theorem],

!http://upload.wikimedia.org/math/1/4/5/1455314a78f39a594485adbaf74d63f9.png!

figure out how many pixels go along th diagonal. You know a (2560) and b (1440), so you can figure out c. I get 2937 pixels along the diagonal. That diagonal is 27 inches, so the pixel density (pixels per inch) is 2937 divided by 27, or about 109 ppi.

For the 24-inch display, using the same math, it is only about 94 ppi.

So objects on the new display will look about 10% smaller than they would look on the old display. The new display will also look more sharp for the same reason. And as I mentioned above, the new display has 60% more pixels to work with compared to the old display.

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Answer 10

Cole29

Level 1

0 points

Oct 25, 2009 6:15 PM in response to Kenichi Watanabe

He doesn't care about screen resolution or pixel count. He's interested in the actual physical size of the viewable area in inches because he's dealing with actual physical space issues in his office.

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Answer 11

emmotive

Level 1

4 points

Oct 29, 2009 12:02 PM in response to Kenichi Watanabe

So objects on the new display will look about 10% smaller than they would look on the old display. The new display will also look more sharp for the same reason. And as I mentioned above, the new display has 60% more pixels to work with compared to the old display.

This reduction in size applies only for raster images - vector images, provided set-up is correct, will display at the same size. Vectors will look sharper though.

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Answer 12

emmotive

Level 1

4 points

Oct 29, 2009 12:04 PM in response to emmotive

By the way, has anyone answered the question of how many millimetres high and wide the 27" display corresponds to? I'm particularly interested whether it can display an A2 size paper (420mm high x 594mm wide).

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Answer 13

emmotive

Level 1

4 points

Oct 29, 2009 12:15 PM in response to emmotive

emmotive wrote:
By the way, has anyone answered the question of how many millimetres high and wide the 27" display corresponds to? I'm particularly interested whether it can display an A2 size paper (420mm high x 594mm wide).

Using information given above, 1440 x 2560 at 109 ppi equates to 336mm high x 596mm wide - so A2 page fits only in width full-screen, being about 8.4cm short in height. Anyone else confirm this?

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