# How many Pixels in 1cm?

hello,

can anyone help me with the answer to the following question? as i hav a keen interest in animation i find myself having to know the difference between the two and i dont actually know, so i am often left to guess:

Q: How many Pixels (square things that a picture is made up of when displayed on a pc) are there in 1cm?

well, this question has a lot of variables you have to deal with. There is what, 2.5 square cm in one inch? Right. Then you have to find out what the resolution is of the image. On a standard monitor, you will get something like 1024x768, sometimes 800x600, and that is the pixelation. so, after determining the pixelation on your monitor, you would have to figure out what 1 square cm is on your monitor. Then, after you find a sq cm, you will have to determine the total square cm of the monitor. Take that figure, and divide it by your resolution, and you should get a ballpark figure. This is a tough one to figure out, because there are so many variables. Good luck…

A reasonable rule of thumb is that most screen images are produced at 72dpi (dots per inch), which translates to around 29 pixels per linear centimetre.

Although you can answer the question for a Mac. Macs have a fixed screen resolution of 72 dpi. Whenever they make a bigger monitor, they increase the number of pixels accordingly.

So, 1 cm = 0.39 in. 0.39 in * 72 dpi = 28 pixels/cm.

The pixel density varies widely. The oft-quoted standard is 72 dots per inch, but that is almost never actually true. My monitor here at work is roughly 12 inches wide and is currently in 1152x864 mode, which makes the horizontal pixel density about 96 dpi. I could kick it down to 640x480 or up to 1280x960; in the former the density would be about 53 dpi, and in the latter around 106 dpi. At home I use 1280x960 usually, but on a much larger monitor so the dot density is around 80 dpi.

Even if you know exactly which monitor and exactly which video mode the user is using, you still can’t be sure because virtually all monitors have vertical and horizontal size adjustments. It is nearly impossible to get accurate size calibrations for computer monitors these days.

And although you said “animation”, it should also be pointed out that printers are capable of very very high resolutions. 300 dpi is common, and 1200 or 2400 dpi is not unusual for graphic printers. I think in these cases there is not usually a one to one mapping between pixels and dots, though it would certainly be possible.