23. LCD Resolutions and Ratios (Part 2)
by orev
From Notebook Review
When you're looking for a laptop (or any type of screen), one of the things you should look at is the screen resolution. Some people care more about the size of the screen, but to me, it's both the size and the resolution that are important. The more pixels on the screen, the more stuff you can see at once.
While shopping recently for a laptop, I kept coming back to the question of: "Will the display resolution at this screen size be too big or small for me to read comfortably?" My current monitor has a nice size, and I wanted to be able to compare my monitor with the laptops out there. Of course, I can't take my monitor everywhere to compare.
This led me to the idea of looking at the DPI, or "Dots Per Inch". DPI measures how many dots (pixels) there are in 1 inch across or down on the screen. Because this measurement is specifically tied to a physical measurement, you can be sure that no matter what the resolution of the screen is, the DPI will tell you exactly how it will look.
I calculated the DPI for many common screen sizes at common resolutions, allowing a very direct comparison of DPI for these different screens. Here are the charts, broken down by aspect ratio (and you thought that learning the pythagorean theorum and all about sin/cos/tangents was useless!):
| Diagonal (inches) | 2560x1600 (WQXGA) | 1920x1200 (WUXGA) | 1680x1050 (WSXGA+) | 1440x900 (WXGA+) | 1280x800 (WXGA) |
|---|---|---|---|---|---|
| 12.1 | 250x249 | 187x187 | 164x164 | 140x140 | 125x125 |
| 14.1 | 214x214 | 161x160 | 141x140 | 120x120 | 107x107 |
| 15 | 201x201 | 151x151 | 132x132 | 113x113 | 101x101 |
| 15.4 | 196x196 | 147x147 | 129x128 | 110x110 | 98x98 |
| 17 | 178x177 | 133x133 | 117x116 | 100x100 | 89x89 |
| 19 | 159x159 | 119x119 | 104x104 | 89x89 | 79x79 |
| 20 | 151x151 | 113x113 | 99x99 | 85x85 | 76x75 |
| 22 | 137x137 | 103x103 | 90x90 | 77x77 | 69x69 |
| 24 | 126x126 | 94x94 | 83x82 | 71x71 | 63x63 |
| 27 | 112x112 | 84x84 | 73x73 | 63x63 | 56x56 |
| 30 | 101x101 | 76x75 | 66x66 | 57x57 | 50x50 |
| Diagonal (inches) | 1600x1200 (UXGA) | 1400x1050 (SXGA+) | 1280x960 | 1024x768 (XGA) |
|---|---|---|---|---|
| 12.1 | 165x165 | 145x145 | 132x132 | 106x106 |
| 14.1 | 142x142 | 124x124 | 113x114 | 91x91 |
| 15 | 133x133 | 117x117 | 107x107 | 85x85 |
| 17 | 118x118 | 103x103 | 94x94 | 75x75 |
| 19 | 105x105 | 92x92 | 84x84 | 67x67 |
| 20 | 100x100 | 87x88 | 80x80 | 64x64 |
| Diagonal (inches) | 1280x1024 (SXGA) |
|---|---|
| 12.1 | 135x135 |
| 14.1 | 116x116 |
| 15 | 109x109 |
| 17 | 96x96 |
| 19 | 86x86 |
| 20 | 82x82 |
Some of those size/resolution combinations don't exist (you'll probably never be able to get a 12.1" screen with a resolution of 2560x1600).
OK, how do you use these charts?
- Figure out the resolution and size of your current display. To find the size of your display, take out a ruler and measure diagonally from corner to corner. To find the resolution, right-click on your desktop, choose Properties, then go to the settings tab. You will see a slider with the "screen resolution" listed.
- Look up your monitor on the chart. For example: if you have a standard (4:3) format 17" display, with a resolution of 1400x1050, then your DPI is 103x103.
- Now you can look at other DPI numbers in the chart and see what else matches up to your monitor.
Some notes on DPI:
- Bigger numbers mean smaller letters on the screen.
- Windows generally assumes you have a 96dpi display, no matter what you ACTUALLY have. At the moment, it's not possible (AFAIK) for Windows to automatically know what the actual DPI is without you telling it.
- I'm not sure how much this relates to DPI settings in Photoshop or other programs like that
- You can compare this to printed paper too. As far as I know, printed material is usually around 300 dpi.
