1 inch = 6 picas = 72 points
From top to bottom:
1, 2, 3, and 4-point rules
Point size is a measurement
that would include room for
all the caps, ascenders and
left: Times; right: Helvetica
Both are the same point size
A standard system of measurement within typography came about in the late 19th century. Prior to that, different type foundries had different ways of measuring their own type. So, mixing type from various foundries was quite difficult.
What’s unusual for younger typographers today is not so much the measurement system, but that a few terms from these metal type days and are still used today. “Leading” just doesn’t seem like the logical choice now to you whippersnappers.
But, I appreciate this. The nostalgia of the vocabulary helps to instill that there’s a long history to this fine craft. And, Peatah’s mission is to promote the artistry of type—no matter what the technology.
With that brief explanation, let’s start with some of the basic terms and descriptions of measurements at the left.
You can see from the short (but enlarged) section of a pica ruler the normal inch measurement on one side and the numbers on the opposing side are picas. Then, the smallest tick marks represent 2 points each. So, there are 12 points
in each pica, and 6 picas per inch.
Picas and points are used for measuring all things type, plus more. The next image down shows that points are also used to measure the weight of lines, or rules.
So, how do you measure type? If you set Helvetica Bold, 18 point, are the capital letters 18 points high? No.
This is a point of confusion since this system comes from the metal type days. Metal type is cast—letter by letter—on individual blocks. All the blocks of a specific size typeface are all the same height. So, the blocks have to be tall enough to contain the caps, the ascenders, and the descenders. Look at the red lines above and below the peatah.org lettering at left. These represent the top and bottom of the type blocks. Each block has to be uniform in height so that the font has a consistent baseline. See how the ascender on the lowercase h extends higher than the capital P?
The point size is based on the height of the type blocks for the specific font. Some typefaces have tall ascenders or long descenders. Some typefaces have taller x-heights or wider characters. This means the same word set the same size in two different typefaces may look as if they are two different sizes. (See the Times Roman and Helvetica 55 Roman “type” examples at left.)
On the next measuring up page, let’s look at line spacing, line measurements and the like. This will get us back to that crazy “leading” term ...
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