Metric Typography Units

From: Frank Farance (
Date: Fri Jan 15 1999 - 12:18:10 EST

At 01:29 1999-01-14 +0000, Markus Kuhn wrote:
> Mirko Raner wrote on 1999-01-13 19:00 UTC:
> > I would like to know whether there are any standards or maybe ISO
> > recommendations about typographic units (eg, point, pica, ...).
> > The special problem is that there are two different definitions of the
> > unit "point". The PostScript standard treats 1 point as 1/72th of
an inch.
> > In conjunction with digital typesetting systems such as TeX 1 point is
> > defined to be 1/72.27th of an inch.
> Asking for an ISO definition of the "point" is the wrong question.
> Typography really should only use metric units like *any* other modern
> field of science and technology. There is absolutely no need for special
> length units in typography.

Lots of industries have special measurements. Whether a "point" is 1/72
inch or its metric equivalent is irrelevant. The point is that a
"point" means the same size -- this issue is (according to Mirko)
whether it's 1/72 or 1/72.27 (replace the metric equivalent if you like).

So what do I choose in my word processor: 10 point or 2.17mm? Since
most users aren't measuring the characters (and they vary in width
anyway), the units are arbitrary. Just like photographic film speed:
ISO 400 speed (easy for the user to use) vs. some chemical equivalent.

In aviation, we have nautical miles (geo-based measurements, like
meters, but using a different scale). As a pilot I rarely have to
convert NM (6080 feet) to statute miles (5280 feet) or KM. Aviation got
it from maritime. It's a lot of tradition, etc., but there is common
(international) understanding. All pilots fly altitude in feet (except,
I've heard, in Russia). The only place I have to convert feet to meters
is on runway visibility ... but just a guestimate is close enough (300
meters is roughly 1000 feet).

> ... [From a separate E-mail ...]
> People not trained as typographers will find it much easier to use
> metric fonts than point fonts, because they can transfer the metric
> estimation skills they have aquired elsewhere and do not have to get
> used to a completely new set of units instead.
> But feel free to test how your students estimate font sizes
> in centieggs as opposed to millimeters ... :-)

Given the cost of conversion, in many industries, one must question the
benefit. When users aren't directly making measurements, arbitrary
units may be better (usability and convenience) than metric equivalents.
In other words, if you never have to convert eggs to millimeters, who

> ...
> Summary: Like all other non-metric units, points (all of them), picas,
> ciceros, cpi, dpi, lpi, etc. are a real mess and should be replaced by
> the millimeter as the one and only unit for every length measure in
> typography as soon as possible (paper sizes, column width/length/
> distances, font sizes, font heights, etc.). Everything else is just
> ridiculous historic ballast and it boggles the mind that we still use it
> and waste a lot of time with converting units. Surely some old
> typographers will turn out to be conservative and mentally inflexible
> and express their irrational love for the points, but we can't continue
> this unit nonsense forever, even if it means breaking quite some
> inertia.

A nice academic argument -- if you were a CEO paying for this, you might
have a different perspective. I'm not opposed to using metric
measurements, I'm just pointing out that when thinking about
measurement, there are a good number of factors involved ... and
usability, history, knowledge base, and convenience may be considerations.

Frank Farance, Farance Inc. T: +1 212 486 4700 F: +1 212 759 1605
Standards, products, services for the Global Information Infrastructure

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