STEP 3: A Beginners’ Guide to Kerning Your Fonts

When I was still in design school, I had a fantastic opportunity to study typography with an exceptional graphic designer and a One Club Hall-of-Famer, Rob Lawton. He taught me to kern type by hand, not on computers. I had to trace letterforms on vellum paper and adjust kerning manually. If I made a mistake, I pretty much had to start the entire sheet all over again. In retrospect, the hands-on approach helped me understand kerning in-depth and never forget what I learn. After all, this skill has served me well for the past couple of decades of my graphic design and art direction career.

However, it was not until I started working on my first typeface that I realized the complexity of kerning a font. As a type designer, you not only have to deal with the front end of kerning the way a graphic designer or an art director does, but you also need to make sure the back end of it is well-organized. From my experience, the critical success lies in the two backend steps you need to complete before kerning an entire typeface: setting the side bearings and setting the kerning groups.

SETTING THE SIDE BEARINGS

The Left Side Bearing (LSB) and the Right Side Bearing (RSB) are the space allocated to the respective sides of each glyph. Setting proper and consistent side bearings will help reduce unnecessary kerning pairs. Moreover, it will save you more time than you ever imagine. Trust me. I learned this the hard way while I was working on my first typeface. I obliviously rushed through the side bearings before realizing my monstrous mistake. As a result, I had to delete all kerning pairs and wasted a few weeks’ worth of work. It was a monumental step back, but much needed, to reset consistent side bearings.

Figure 1 – The left side bearing (LSB) and the right side bearing (RSB) of H and E. [Font: Aldero™ Light]

The above photo shows that the LSB and RSB of the H and the LSB of the E are set at the same width because they share identical edges. However, the RSB of the E is set at narrower width to compensate for the negative space surrounding the E.

Figure 2: Keep letterspacings (green spaces) visually consistent as much as possible. [Font: Boxr™ Light]

In Figure 2, the width of both green spaces looks roughly the same even though the one on the right is narrower. This is because the LSB and RSB of the O are thinner than those of the benchmark pair, H and N, to compensate for the extra negative space at the top and bottom corners of the O. If you set the side bearings well, you don’t need it to kern the HO pair.

Figure 3: Examples of LSB and RSB of S, X, and Z compared to H.

Now let’s apply what you learned above to more glyphs. The S has a similar outer form to the O but with two openings. To compensate for the extra negative space, you should set the LSB and RSB of S slightly narrower than those of the O. And because the Z has the largest openings on both sides, its side bearings should be the thinnest in this group. From here, you can keep going until you thoroughly set the side bearings of all glyphs.

SETTING THE KERNING GROUPS

The second backend step you must complete before starting to kern is setting the left kerning groups (LKG) and the right kerning groups (RKG). If done correctly, all members of the same group will automatically be assigned the same kerning values for all their kerning pairs. It will tremendously save you time in the kerning process. So make sure you have thoroughly set them before you start kerning.

Figure 4: The top row shows the glyphs with the same LSB, RSB, LKG, and RKG. The bottom row shows the glyphs with the same LSB and LKG but different RSB and RKG. [Font: Aldero™ Light]

To set kerning group, you should look for the similarity at the left and the right edges of each letter. For example, from Figure 4, the three letters in the top row share identical straight side edges. Therefore, they should have both the left and the right kerning groups and side bearings set consistently. However, in the bottom row, you will notice that only the left edges of these characters are identical to that of the H in the top row. Therefore, all the bottom row characters should only have the same LKG and LSB as the H.

KERNING

Kerning is the adjustment of space between two individual letters. In type design, kerning is a much more complicated and time-consuming task than kerning just a few headlines. It requires consistency and persistence. As a type designer, your job is to make letterspacing for the entire typeface look as harmonious and consistent as possible.

Figure 5 – Kerning pair “AV” and the benchmark pair “HH.” [Font: Boxr™ Light]

After completing both backend steps mentioned earlier, you will likely still need to kern many letter pairs. Let’s use an AV pair, in Figure 5, as an example. Even if you set the side bearings to the minimum for both characters, the negative space between them is still too broad. That’s when kerning comes into play. Again, be sure to compare the letterspacing with your benchmark pair, such as an HH, NH or NN, for consistency.

To help ease your kerning task, you need some tricks up your sleeves. I want to suggest three that can help you focus on the letterspacing and the edges of letterforms: white type on a black background, upside-down type, and blurry type. Conveniently, for the Glyphs app users, these visual modes are built-in. So you can choose just one or any combination that suits you.

Figure 6: Three visual modes that can help improve your kerning. [Font: Boxr™ Light]

The white type on a black background will trick your eyes to look at the letterspacing as positive spaces. The black background will also cause less strain on your eyes when staring at the computer screen for hours at a time. 

The upside-down type will fool your eyes to look at each character as a geometric shape rather than what it represents. This way, you will focus on the letterspacing and its surrounding forms with fewer distractions.

Have you ever squinted your eyes while kerning type? When you do so, the characters will appear blurry. It helps you focus on the letterforms and the negative spaces better. Glyphs app can make your type look blurry, so you don’t have to squint your eyes. It also allows you to adjust how blur you want.

EXTRA STEPS TO IMPROVE FONT USER EXPERIENCES

Figure 7: We kern lowercases to both sides of the uppercases, so you don’t have to. [Font: Boxr™ Light]

At R9 Type+Design, we aspire to create user-friendly fonts. Therefore, we took an extra step to kern lowercases to both the left and the right sides of the uppercases. It is an optional practice that only some type foundries would implement. However, we have seen more and more usages over the years, especially when you want to separate words without word spacing (e.g., company names and hashtags).

Figure 8: The Letterspacing between L and A is too large that a simple kern would make it consistent. [Font: Aldero™ Light]

From time to time, you will come across substantial negative space in a pair such as LA in Figure 8. A simple kern will not be enough to solve the letterspacing issue. Instead, you can create a discretionary ligature for such a pair as an option for your customers. This way, you can manipulate the letterform as well. But try not to overdo it. Otherwise, the L may no longer be recognizable.

Figure 9 – Embedded kerning for inconsistent word spacing. [Font: Boxr™ Light]

Last but not least, sometimes, even minor details can make significant differences. This particular one derives from my graphic design pet peeves. It is a bit annoying when I have to adjust word spacing, especially for words that start or end with A, L, T, V, Y (see Figure-9). The negative space of these characters often causes visually inconsistent word spacing. Therefore, I decide to kern these characters to both sides of the “Space” glyph (Unicode U+0020) for all my typefaces. Voila, problem solved for my font users! Just be mindful not to overdo it. For example, the word spacing of ”CALL TIME” appears wider than that of “IN TIME.” So, if you heavily compensate for the T, it may work for one situation but not another. The key is to find the middle ground kerning value that would be a good compromise.

Now that you have learned some kerning basics, it’s time for you to start practicing. Learning by doing is the best way to go. If you have more questions, feel free to check out the helpful links below. Be sure to subscribe so you won’t miss our next post. See you then!

HELPFUL TYPE KERNING LINKS:

Setting Side Bearings in Glyph: https://glyphsapp.com/learn/spacing
Kerning and Setting Kerning Group in Glyph: https://glyphsapp.com/learn/kerning
Kerning Tips: https://99designs.ca/blog/tips/11-kerning-tips
Basic Kerning Text: http://www.as8.it/type/basic_kerning_text.html
More Kerning Text: https://pangrampangram.com/blogs/journal/kern-king-is-dead-long-live-kern-king-br-the-great-template-for-kerning-types