About font sizes

[deko]

As I understand it, most browser manufacturers have agreed on 16px for their
default font size.

So, this should be an accurate conversion for percentages:

px %

16 = 100
14 = 87.5
13 = 81.25
12 = 75
10 = 62.5

I assume it's better to stick to a percentage that will yield a round number -
rather than using something like 90% to get 14.4. A browser will just round up
or down to a font size it can display, correct?

As for em, am I correct in saying 1em = 16px?

Does that mean 1.2em is 19.2px (rounded by the browser to 19px - if the default
size is 16)?

[David Dorward]

Re: About font sizes

deko wrote:
[color=blue]
> As I understand it, most browser manufacturers have agreed on 16px for
> their default font size.[/color]

I think it is more of a case that 16px is easy to read for a majority of
users, so Microsoft set it as their default, and other browser vendors
followed suite.

Its overridable by the user though.
[color=blue]
> So, this should be an accurate conversion for percentages:[/color]

No, since you don't know that the user hasn't expressed their own
preference.
[color=blue]
> As for em, am I correct in saying 1em = 16px?[/color]

No, see above.

--
David Dorward <http://blog.dorward.me .uk/> <http://dorward.me.uk/>
Home is where the ~/.bashrc is

[deko]

Re: About font sizes

> No, since you don't know that the user hasn't expressed their own[color=blue]
> preference.[/color]

assuming 16 is the default, and this is what the user is currently using, and it
has not been overridden....

then my math is correct.

A basic guide (based on 16) might look like this (assuming the above statement!)

137.5% = 22px (h1)
125% = 20px (h2)
112.5% = 18px (h3)
100% = 16px (large)
87.5% = 14px (medium)
81.25% = 13px (small)
75% = 12px (smaller)
62.5% = 10px (legalese)

The point is, if you are going to use percentages, you might as well adjust to a
font size that the client browser can display. If 16 is the default, then it's
best to use that as a basis for adjustment.

[David Dorward]

Re: About font sizes

deko wrote:
[color=blue][color=green]
>> No, since you don't know that the user hasn't expressed their own
>> preference.[/color]
>
> assuming 16 is the default, and this is what the user is currently using,
> and it has not been overridden....[/color]

That is a lot of assumptions.
[color=blue]
> The point is, if you are going to use percentages, you might as well
> adjust to a font size that the client browser can display.[/color]

Systems can round font sizes to something acceptable, so there's not really
any point in worrying about it.


--
David Dorward <http://blog.dorward.me .uk/> <http://dorward.me.uk/>
Home is where the ~/.bashrc is

[Chris Hughes]

Re: About font sizes

[color=blue]
>deko wrote:
>[color=green][color=darkred]
>>> No, since you don't know that the user hasn't expressed their own
>>> preference.[/color]
>>
>> assuming 16 is the default, and this is what the user is currently using,
>> and it has not been overridden....[/color]
>
>That is a lot of assumptions.
>[color=green]
>> The point is, if you are going to use percentages, you might as well
>> adjust to a font size that the client browser can display.[/color]
>
>Systems can round font sizes to something acceptable, so there's not really
>any point in worrying about it.
>
>[/color]
16px? That's eNORMous! (I just tried it.) 12px would be more reasonable,
surely?
--
Chris Hughes
"Reality is that which, when you cease to believe, continues to exist."

http://www.epicure.demon.co.uk

[Sid Ismail]

Re: About font sizes

On Sat, 10 Jun 2006 17:42:57 +0100, Chris Hughes
<chris.hughes@e picure.demon.co .uk> wrote:

: 16px? That's eNORMous! (I just tried it.) 12px would be more reasonable,
: surely?


Depends on the User's settings, as David said.

http://www.elsid.co.za/download/css_fontsizes.htm

Sid

[Beauregard T. Shagnasty]

Re: About font sizes

Chris Hughes wrote:
[color=blue]
> 16px? That's eNORMous! (I just tried it.) 12px would be more
> reasonable, surely?[/color]

It would depend entirely on your visual acuity. Yours may be better than
mine.

A friend of mine has a 20 or 21" monitor set to 800x600 resolution so
she can read it. Me, I can read it from the next room.

--
-bts
-Warning: I brake for lawn deer

[Alan J. Flavell]

Re: About font sizes

On Sat, 10 Jun 2006, deko wrote:
[color=blue]
> As I understand it, most browser manufacturers have agreed on 16px
> for their default font size.[/color]

As I understand it, many discerning web users have agreed to choose
the default font size which they prefer to read.
[color=blue]
> So, this should be an accurate conversion for percentages:
>
> px %
>
> 16 = 100
> 14 = 87.5
> 13 = 81.25
> 12 = 75
> 10 = 62.5[/color]

Nobody seems to have come right out yet and told you that you're
chasing the wrong hare. There's nothing useful that you could do with
this information, even if it *is* a particular "manufacturer's "
default.
[color=blue]
> I assume it's better to stick to a percentage that will yield a
> round number -[/color]

I'm not sure why. It's only a rendering proposal, after all.
There's no way you can be assured of getting whole-numbers by
specifying a percentage for all of us, no matter whether we configured
our em unit as 13px or 16px or 25px or whatever - according to our
display properties, our eyesight, whatever.

Better to aim at a size which readers can comfortably read. And for
normal body text, that's axiomatically 1.0em. Recommended reading:

http://www.xs4all.nl/~sbpoley/webmatters/fontsize.html

There *is* no fixed table of correspondences between absolute size
units and relative size units, nor can there be: that's the whole
reason for having both[1] kinds, after all. So don't confuse yourself
by trying to derive one. As the CSS specification perceptively
remarks:

"Absolute length units are only useful when the physical properties
of the output medium are known."

- which in the case of general WWW design, most assuredly they are
*not* known.

good luck

[1] OK, technically speaking, CSS px units are neither absolute nor
relative, in this sense, but are yet another kind of unit. But, so
far, rarely implemented to specification

[Tony A.]

Re: About font sizes

Chris Hughes wrote:
[...][color=blue]
> 16px? That's eNORMous! (I just tried it.) 12px would be more
> reasonable, surely?[/color]

You're not mixing units are you? 16px looks like 12pt on my system.

[David Dorward]

Re: About font sizes

Chris Hughes wrote:
[color=blue]
> 16px? That's eNORMous! (I just tried it.) 12px would be more reasonable,
> surely?[/color]

That depends on the resolution of the screen and its physical dimensions.
16px is tiny on an 21" 800x600 display but huge on a 14" 1600x1200 display.

Larger then needed is far better then too small to read, so its a sensible
default for systems to adopt. Users can then change it to something more
acceptable for their resolution, screen size and eyesight.

--
David Dorward <http://blog.dorward.me .uk/> <http://dorward.me.uk/>
Home is where the ~/.bashrc is

[Jukka K. Korpela]

Re: About font sizes

David Dorward <dorward@yahoo. com> scripsit:
[color=blue]
> Systems can round font sizes to something acceptable, so there's not
> really any point in worrying about it.[/color]

Unfortunately, there is.

Typography rules say, among other things, that a change in font size should
be clear enough so that it does not look like an error. The mileage varies,
but let us assume that a 10% increase is desired. So if we say font-size:
110%, what will happen? The browser computers the absolute font size and
then selects the closest actual font size it can use - at the simplest,
selecting among differently sized fonts for the given font family
(typeface). For all we can know, that size could be identical to the basic
font size (when only a few sizes exist). Or it might be almost 20% larger
than the basic font size.

For example, if the basic font size is 12pt, then 110% yields 13.2pt, which
I would expect to get rounded to 13pt. However, for Times New Roman, I seem
get a bigger font (13.5pt?), which is rather big and looks bolded. If I set
the font size to a smaller percentage, there's the risk of getting no font
size increase, for some combinations of font face and basic size.

--
Jukka K. Korpela ("Yucca")

http://www.cs.tut.fi/~jkorpela/

[Neredbojias]

Re: About font sizes

To further the education of mankind, David Dorward <dorward@yahoo. com>
vouchsafed:
[color=blue]
> Chris Hughes wrote:
>[color=green]
>> 16px? That's eNORMous! (I just tried it.) 12px would be more
>> reasonable, surely?[/color]
>
> That depends on the resolution of the screen and its physical
> dimensions. 16px is tiny on an 21" 800x600 display but huge on a 14"
> 1600x1200 display.[/color]

Surely you meant that the other way around?

--
Neredbojias
Infinity has its limits.

[deko]

Re: About font sizes

> Typography rules say, among other things, that a change in font size should be[color=blue]
> clear enough so that it does not look like an error. The mileage varies, but
> let us assume that a 10% increase is desired. So if we say font-size: 110%,
> what will happen? The browser computers the absolute font size and then
> selects the closest actual font size it can use - at the simplest, selecting
> among differently sized fonts for the given font family (typeface). For all we
> can know, that size could be identical to the basic font size (when only a few
> sizes exist). Or it might be almost 20% larger than the basic font size.
>
> For example, if the basic font size is 12pt, then 110% yields 13.2pt, which I
> would expect to get rounded to 13pt. However, for Times New Roman, I seem get
> a bigger font (13.5pt?), which is rather big and looks bolded. If I set the
> font size to a smaller percentage, there's the risk of getting no font size
> increase, for some combinations of font face and basic size.[/color]

Yes, this is exactly what I am concerned about.

If I want to avoid specifying px for font sizes, using percentage instead, and
use this as a rough guide:
[color=blue]
> 16 = 100
> 14 = 87.5
> 13 = 81.25
> 12 = 75
> 10 = 62.5[/color]

I run the risk that a font may not have a 13px size (81.25%)

Furthermore, if the user has set his default font size to something other than
the manufacturer's default (16px), then it's a crap shoot what size font will
render at a particular percentage.

So percentage may make it easier for the user to adjust the font size, but px is
the only way to have absolute control of what gets displayed.

Yet it seems IE is the only browser that cannot adjust px-specified font sizes.
If my audience is strictly FF users, then why not specify px font sizes? They
are just as adjustable as anything else.

[David Dorward]

Re: About font sizes

Neredbojias <http://www.neredbojias .com/fliam.php?cat=a lt.html> wrote:
[color=blue][color=green]
>> That depends on the resolution of the screen and its physical
>> dimensions. 16px is tiny on an 21" 800x600 display but huge on a 14"
>> 1600x1200 display.[/color]
>
> Surely you meant that the other way around?[/color]

Err. Yes.

--
David Dorward <http://blog.dorward.me .uk/> <http://dorward.me.uk/>
Home is where the ~/.bashrc is

[David Dorward]

Re: About font sizes

deko wrote:
[color=blue]
> Furthermore, if the user has set his default font size to something other
> than the manufacturer's default (16px), then it's a crap shoot what size
> font will render at a particular percentage.[/color]

And since you don't know if the user has specified their preference as
something other than 16px, its /always/ a crap shoot.
[color=blue]
> So percentage may make it easier for the user to adjust the font size, but
> px is the only way to have absolute control of what gets displayed.[/color]

Thank goodness for minimum font size options...
[color=blue]
> If my audience is strictly FF users, then why not specify px font sizes?[/color]

Percentage also allows the author to respect the user's font size preference
and leave body text at whatever the user specified.

--
David Dorward <http://blog.dorward.me .uk/> <http://dorward.me.uk/>
Home is where the ~/.bashrc is