Monospace Font Spacing

Mithil Mogare

Monospace fonts are distinct from standard kerning fonts. I researched numerous mono fonts on the market while spacing monospace font. It raised some questions and doubts, and I'm experiencing some difficulties with monospace design spacing. The width of the matrices is the same for all glyphs, however the glyphs are not centred in the matrices. Some have irregular spacing on both ends (RSB and LSB).

The following are the questions:

1. What is the standard accepted method or practise for adjusting the spacing or side bearings of monospace fonts?
2. How do you determine equal spacing between all glyphs in a monospace font?
3. How did the designers arrive at the precise quantity of RSB and LSB in monospace font?
4. What are your biggest pain points and sensitive areas while spacing mono fonts?
5. What guidelines do you follow while spacing mono fonts?

Your input would be incredibly valuable to me, and I would be most grateful for any guidance you might be able to provide. I cannot thank you enough for your time and consideration,

Regards,
Mithil Mogare
(+91) 8888 24 1144

John Hudson

1. There isn’t a single, standard approach to spacing monospaced or fixed-width typefaces, because there isn’t a single approach to their design. The important thing to bear in mind is that because the advance width of the glyphs is constant, you are obliged to adjust the glyph shape to the spacing, not the other way round. Obviously, this means the most important decision in the design is what that constant width is going to be: if it is very wide, narrow letters like I i l will be a challenge; if it is very narrow, wide letters like M W m will be a challenge.

2. You can’t determine equal spacing between all glyphs in a monospaced font, because you need to make exceptions for narrow and wide letters having, respectively, larger and smaller sidebearings than medium width letters.

3. You start with the medium width letters a b c d e etc, and aportion sidebearings for these much as you would when spacing proportionally, i.e. looser sidebearings for straight stems versus tighter sidebearings for bowls. Narrow letters tend to get oversized serifs or bars in monospaced donts, to help fill up the horizontal space, but will still have a lot more white space around them. Wide letters have to be horizontally compressed to fit, and typically have minimal sidebearings: just enough that a sequence of two or more wide letters still have a little space between them.

4. Wide letters are usually the biggest pain point, especially in a bold weight, where they not only need to be compressed but often end up with lighter stroke weights than other glyphs.

5. Do experiments with a few narrow, medium, and wide letters before finalising your decision about what the constant width is going to be. Also, if you are planning a monospaced family with mulitiple weights, do trials of the most challenging letters at the heaviest and lightest weights. You don’t want to be in a situation in which you have done all the glyphs in one weight and then realise that the other weight doesn’t work on the advance width you have chosen.

Craig Eliason

Letters (other than quite symmetrical ones) are not centered in their advance width (i.e. have different sidebearings) because mathematically identical sidebearings will not result in optically even spacing. An L or an r for example is heavy on the left side and quite open on the right, so with mathematically even sidebearings it will look like it's crowding the previous letter and too far from the following letter. 
Since this is an optical rather than mathematical effect, the solution lies in optical judgment rather than mathematical formula. Once satisfying, symmetrical sidebearings are set up for a letter like H (and after considering the advance-width decisions John mentioned above), it can become a "control character." Then you can type a string like "HHLHH" and skootch the L sideways so that it looks centered to your eye. 
(In the font editor, with a monospace design you obviously want the advance width to stay constant, so instead of adding units to one sidebearing and then subtracting them from the other, it's easiest to select all the paths and move them sideways at once.)

Nick Shinn

Here’s a good test word: mammillaria
Also: Ammunition
And: David Hemmings

I’m sure you can find some words that you like—in fact, searching for “worst case scenario” test words, and comparing your design with other monowidth typefaces, in such words, can be quite interesting and useful.

I just googled “double m words” and came up with a Scrabble list, that’s where I found “mammillaria”. Then I wondered what it meant, and checked Wiki. You learn something new every day!

Johannes Neumeier

While on the subject of test words, here a couple of mono-space tricky samples from Finnish, which has a bunch of uncommon (in English anyway) double-vowels and double-consonants:

niinikään miinanraivaaja uutisvaahtimme puuttellinen puutiikki pellavaliina kukkaruukku …

Craig Eliason

Now I'm pondering: does using foreign or otherwise unfamiliar words lend a "defamiliarization" effect that makes it easier to see spacing issues? Or if I have no pre-existing sense of what the word should like is it instead harder to see them?