96dpi - why bigger font?

Hi there!

I’ve gone through Wikipedia and a few other websites but still found no satisfactory explanation…

The problem is:
12pt font will look bigger on Windows 96 dpi screen than on 72 dpi Mac screen.

My logic is:
If both screens have the same inch (2,54cm x 2,54cm) and one of them displays more pixels in that same inch, elements should be smaller not bigger.

Theoretically - if one screen A displays 100px and screen B 200px in one inch, a 100px x 100px image will be twice as small on the screen B.

Ok someone will tell me “when it comes to fonts from the question the unit is point not pixel and you need to calculate: 12pt=1/6inch so on 72dpi Mac it will be 12px and on 96dpi Win 1/6inch = 1/6 of 96px = 16px”

Yeah right but the inch is still the inch so if Mac has 72px in the inch and Win has 96px in the same inch, 12px on Mac font should equal 16px on Win screen.

Can you help me out with this? Where am I wrong? I’ve got confused…

If the font size is 12pt then the size should be the same in all circumstances since there are always 72 points in an inch. It might look bigger at 96ppi than it does at 72ppi because the surrounding content that isn’t measured in points is smaller.

You might get the effect you expect if you were using pixels rather than points for the font size.

The point unit is for “printed media” anyway so you are likely to see a difference on screen… In reality the dpi ‘Text Size’ is a “Logical Inch” computed value. Don’t confuse “logical inches” with “real inches” - very different concepts.

For example we have three; 100px by 100px images, one at 72 dpi, 96 dpi and 300 dpi. It will look the exact same size within a web browser but when printed it will differ.

Basically DPI does NOT apply to video screens; video systems know no concept of dpi at all or any concept of inches either. You should notice that the terms “dpi” or “ppi” simply do not appear in any user manual for any monitor or for any video board.

Hopefully that will help you a little. :slight_smile:

Thanks to you guys for wanting to help in the first place;)

So is the size of the pixel on the screens in both cases identical? I mean 72dpi Mac and 96dpi Windows?

Because then yes - it would make sense. The logical inch is computed to 96 pixels and 1/6 is different on Mac and Win. As a result Win displays bigger.

What I thought was that in the very same inch as measured with a ruler stuck against the screen I would have 72 pixels on Mac and 96 on Win. So logically, the conclusion followed - the Win must be smaller.

Your original question mentioned points rather than pixels as the unit for the font size. They are two different measurements with points being independent of the ppi of the screen.

Another consideration is that a font on the mac may not display identically to the same font on windows even at the same declared size since in both cases they are subjected to processing in the operating system that determines exactly how fonts are displayed (since the text never exactly fits into exact pixels and so needs adjusting).

Glad it helped; it is a very confusing topic and most people don’t realise dpi is a ‘Text Size’ and hence why you get the big “myth” about web images and the so-called “magic number” of 72 dpi.

Thanks for your help guys!