# How is it possible that some 24'' monitors are 16:10 while some others are 16:9?

This might seem like a stupid question but I really can't wrap my head around it. For example Dell has both U2415 (16:10) and U2414H (16:9). Those monitors supposedly have the same screen size, so how is it ever possible that one manages to offer additional vertical screen space while the other doesn't?

The only explanation that I can come up with is that the pixel sizes might be different. But doesn't a single pixel have the same size on all four dimensions? (i.e. it must be a perfect circle shape or a perfect square shape etc. instead of an oval/rectangle. You get what I mean) If it has the same size on all dimensions, then no matter how you make one pixel bigger/smaller and how you arrange the pixels, I don't see how it's possible to get two different aspect ratios on the same base screen size (without distorting the screen content being displayed). Or is my assumption wrong?

• Roald van Doorn has the correct answer here, but one of your premises is wrong. Pixels do not have to be square. In fact, square pixels cannot accurately display PAL or NTSC video. The IBM PC used rectangular pixels via the Color Graphics Adapter. – 8bittree Oct 11 '16 at 21:00

## 1 Answer

The angle under which the diagonal is measured is different. See https://en.wikipedia.org/wiki/Display_size for more information, but basically, the 16:10 is less wide, but higher than the 16:9 version.

To be exact, a 24", 16:10 screen is 20,5"x12,6" and a 24", 16:9 screen is 20,9"x11,8".

• centimetres... not inches – Tetsujin Oct 11 '16 at 18:37
• To add further, the pixel size is of no consequence for the actual, physical dimensions of the screen, at work I use a 4K (3840x2160 pixels resolution) 24" screen next to a normal 16:9 24" screen. Both from Dell, with the same physical dimensions. – R-D Oct 11 '16 at 18:38
• OK, so although they're both called 24'', they're really of two different actual sizes then. – xji Oct 11 '16 at 18:38
• Absolutely: all screen sizes are the diagonal measurement. In addition, the pixel dimensions are different: a typical 16:10 is 1920×1200 pixels; 16:9 is 1920 x 1080. For full-screen, games will crop the viewport, pre-rendered imagery (movies) get either sttretched, zoomed and cropped, or letterboxed – Yorik Oct 11 '16 at 18:38
• @Tetsujin, you're right. I'll fix it. – R-D Oct 11 '16 at 18:38