Origins of Em, En, Ex

I’m reaching out for some clarification, although I feel like this has most likely been discussed. I am reading a text in which there is a conversation around Em & En spaces, the usual talk. Em quads are the full height of the font, En quads are half that, etc. Then they referred to the lowercase height as the “ex” height, which I had never seen before. I’ve always seen it written as x-height.

I want to ask “what are the origins of the names Em, En, and Ex. Are they short for something, or abbreviations?” Does anyone have some old printing text that can describe how these spaces were named? Thank you.

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Here is a workingman’s response.

An M quad is a square quad, or piece of spacing material, having the same size as the type size you are referring to. For instance, a 12 pt M quad is 12 X 12 points. It is called that because the uppercase letter M is often cast on this size.

An En quad is half of an Em quad and is approximately the size which uppercase N’s are cast on. So a 12 pt N quad is 6 pts wide X 12 pts high.

The x height is the height of the lowercase letters in a font (not counting letters with descenders like p or y, or letters with ascenders like l or h).

As an aside, the beauty of the quad and space system is that often, quads and spaces of different sizes are interchangeable, so if you run out of one, you can use the other. For instance, if you run out of 12 pt 2M quads you can use 24 pt N quads because they are the same. If you need 6 pt 3M quads you can use 18 pt 3-to-M spaces because they are the same. And there are many more combinations like this.

Hey Geoffrey,

While usage has giving this idea some verisimilitude, I am fairly certain the Em quad is not called so because it is the shape of an M. I believe this is simply a naming device that was used to distinguish the two spaces, and make it easy for apprentices to remember which space is which. We’ve just become so familiar with this that it’s not often talked about. Same with x-height/Ex height. We often say that this is because it’s the height of the lowercase x, but what I’ve been reading (typesetting books for apprentices from 1890–1910) suggest otherwise. There is no mention of M, N, or x being used as a standard for width or height. This is what I’m looking for someone who might have some earlier printing text that describes this.

Uppercase M’s are cast on quads often as an upper limit to design—it’s easiest to do this because its an already available size. But, I have a few M’s in my collection that are bigger than an Em quad, so it’s a move that’s pretty frequently discarded.

A further note is that if Em & En quads followed this system, the grammar rules for Em dashes and En dashes wouldn’t work properly. En dashes often don’t work the way they were intended, because they’re too similar in size to a hyphen.

I could be completely wrong, but I’m interested in finding out how far back we can read about examples of Em, En and Ex dashes to find out.


To quote from ‘Practical Printing’ by John Southward (London 1900):

‘An em is a unit of measure varying with the bodies of types. It is always equal to the depth or body of the type of which the fount is composed. An em is one-half of the em. These names were given to the measures because in book founts the type for the letter “m” was usually exactly as wide as it was deep, and the type for the letter “n” half as wide as it was deep.’
Note too that the term ‘mutton’ is often used for ‘em’, and the term ‘nut’ for ‘en’ - to help verbal/aural differentiation and to prevent misunderstanding in noisy printing workshops!

Correction to my previous post: third sentence should read:

‘An en is one-half of the em.’

I’ve found two more examples, the first from 1905 in which the terms Em & En are used, and there is terminology attached to each fractioned space. All “quads” are referred to as quadrats.

The second, significantly older (1867) seems to support you both, in referring to an Em space as an M space.

However, neither text makes reference to the Em or Em space as being from M or N despite appearances. I’m hoping to find something from late 18th early 19th century.

image: The Printers Manual, 1867

The Printers Manual, 1867

image: Printing, 1905

Printing, 1905

I am looking at Joseph Moxon, Mechanick Exercises on the Whole Art of Printing, originally published 1683-84, second edition edited by Herbert Davis & Harry Carter, published by Dover,1978. On page 170 of this edition, in his discussion of Casting of Letters, etc., Moxon says: “But besides Letters, there is to be cut for a perfect fount (properly a Fund), Spaces thick and thin, n Quadrats, m Quadrats, and Quadrats.” I am guessing that the last Quadrats are 2-em.



Nice, thank you! I’m at 1818, with “The Printers Guide” and I’m seeing Em, En, Ex, Quadrat, and Fount.

I’ll see if I can find this text on my end. With everyone that’s been here, does anyone have an idea then why the e is added?

image: Printers Guide, 1818

Printers Guide, 1818

For posterity, here is an example from Mechanick Exercises that has an example of m & n quadrant being used. This version is from 1683.

image: mechanickexercis00moxo_0_0267.jpg


image: mechanickexercis00moxo_0_0266.jpg


My guess is the “e” was added to clearly distinguish the letters m and n from the spaces em and en. It would certainly reduce confusion when ordering sorts from a foundry.
I have never seen “ex-height” used in place of x-height; that is unambiguous.

In the U.K letterpress industry compositors called an em space a mutton and en space a nut. In a busy composing room it avoided confusion that might be caused by the similar sounding names of em and en.

So the set of spaces in a case would be mutton, nut, thick, mid and thin and hair spaces where companies used the thin copper spaces.

Mutton was used in the US too in earlier days. That’s why the US version of dicing with quadrats was called Jeffing, (from the comic strip Mutt and Jeff).

parallel-imp, I call bs, the Mutt ‘n’ Jeff cartoon was introduced in 1907, and here is a link to an article from The Morning Press, Santa Barbara, CA, 15 April 1904:

image: Screen Shot 2021-03-04 at 10.32.38 PM.png

Screen Shot 2021-03-04 at 10.32.38 PM.png

Fine. So Mutt and Jeff comes FROM printer’s lingo, which would not be unlikely for a news cartoon.
“Calling bs”? Why do you ALWAYS take the most combative take on everything? Is that why you took so much effort to delete past posts?

Hey parallel_imp & Devils Tail (could we get some first names in here, pen names maybe) It’s fine, no worries. Let’s all assume that everyone is well meaning, and that we’re all here for the greater benefit of printing knowledge sharing, and also check before we post to not sound too combative. I’m guilty of as well.

I’m going to follow up to a post from parallel from earlier, talking about the “ex height” instead of x-height. I have an example here somewhere but I’ll have to track it down later.

At this point, I’d say we’re here:

I concede to Geoffry and Kenneth, and am swayed to their side of the argument. I think that as far as we all can see, M & N quads are named for the size of the type that they resemble. The next step would be to find a piece of literature that says “The M-quadrat and N-quadrat are called so because it is convenient to typeset onto existing spacing material” or the opposite “The M-quadrat and N-quadrat are called so because they resemble the side of a M & N.” I think this is going to be hard before 1700 because I would assume that printers manuals weren’t really thinking about posterity, and were more concerned with getting the work done.

Devils Tail Press

Are you back? I hope so. You have been missed by those who appreciate your willingness to share.


The first documented use of Mutton-quad was in Luther Ringwalt’s 1871 American Encyclopedia of Printing (OED). The adventures of Mr. A. Mutt drawn by Bud Fisher was first shown in the San Francisco Chronicle in November 1907. The San Francisco Examiner (Hearst) lured Fisher over in December of the same year, and it wasn’t until early 1908 that Fisher introduced a character from a madhouse, Jim Jeffries, who thought he was a boxing champion. It is highly doubtful that either character was named for any printing term, but rather started with the dictionary definition, of a mutt being a stupid or foolish person, or simpleton. The “Jeff” character was likely named after James Jackson “Jim” Jeffries (April 15, 1875 – March 3, 1953) an American professional boxer and World Heavyweight Champion.

It might be helpful to remember that Ben Franklin worked as
a comp (in a small shop on Saffron Hill, London near to the tube station) for quite a while, dodging creditors back in the US. Comp room legend here has it that he led a strike for extra pay for setting five point, and won!. Once part of Government in the US he initiated a change of names for sizes of paper so no longer Royal or Double Crown, but Eagle and so forth. I think he may well have brought other technical ideas back with him from the UK apart from political ones. He certainly met John Baskerville.

Harrildplaten, that is the idea that I’m chasing, but I’m not finding much traction that far back. I’m going to be in DC later in the year, and I will see if there is some information at the Library of Congress. I think there is a museum for printing as well (currency, I think) and maybe someone there has an idea.

OK, I stand corrected, so how the hell does “jeffing” come from using “muttons” if unrelated to Mutt & Jeff?

In John Johnson’s “Typographia or the Printers Instructor” Vol. 2, 1824, the terms “m-quadrat” and “em quadrat” are both used in the book and with apparently the same meaning. In my opinion, the size of a capital M, is secondary to the definition of an em, given that the definition of a quadrat in general, is that of a square. And the definition of an em is the square of the type body, as others have pointed out.


I believe that. I am 100% certain that quadrats received a name after there creation that we now refer to as Em & En. What I’m curious about is wether Em & En refers to something else, other than the M & N characters. That they could be short for something, or a prefix.

I think that harrlidplaten also has a good assumption, that since printing comes from a European lineage through the settlement of the US, we probably have some terminology that got lost in between. So for a while my research is going to go to European books.

Thank you both.

You’re making a mountain out of a dead horse. You might just want to start paying attention to the information you have already been given, rather than spending more time in search of an alternate truth. The Em-quad and En-quad terms are in reference to the lowercase characters, the traditional width of each being close to the dimensions you discuss. What more do you really need?

Need more? Read:

Typographical Printing-Surfaces, by Legros and Grant, Longmans, Green and Company, London, 1916

Mutton and Nut are largely unknown terms in the US. Both are missing from the American Dictionary of Printing and Bookbinding, W. W. Pasko, Howard Lockwood & Co, New York, 1894. Legros and Grant mention them both on page 55, but give no origin for the terms, which are likely just an alternative sound for m=mutton, and the same for n=nut. Likely originating as a set of slang terms used by workers in a large city plant in England. Most dictionaries list the origins as in the early 20th century. OED doesn’t mention them at all. Nor are they mentioned in late 19th century, early 20th century English manuals Southward or Jacobi.

Remember that Caxton brought printing to England in 1476 only 25 to 35 years after its invention, so English input into common printing terms is almost as old as printing itself.