Kerning Defaults: Metrics (or Auto), Not Optical

Just to make it extra clear while we wrap the subject of kerning, I do have a preference on kerning defaults, and you should too.

Picture 3

The main message of last week’s piece on kerning is that you should only kern what you have to. Take advantage of the kerning that comes built into your fonts. Do this by setting your default kern settings to Metrics in InDesign, and Auto in Illustrator. Don’t set your default to zero, and don’t set it to Optical.

But Optical sounds so nice.

It does. It’s alluringly named. Here’s what zero does, and what Optical does: Setting the kerning value to zero ignores the kerns in the font data. Setting it to Optical ignores the kerns in the font data, and essentially makes a spacing exception between every character, meaning that it’s more than the troublesome pairs who need it that get kerned, everything gets kerned by a robot that’s not very good at kerning.

Picture 2

The above is InDesign kerning FF Legato based on—respectively—the font’s metrics set by its designer, the font’s spacing values only (no kerning), and based on an algorithm that discards both spacing and kerning values and comes up with its own. Note how Optical sets WA a little loose, and LT and ER tight?

For display work, you’ll probably be able to spot this stuff and fix it. But what I really worry about is when Optical kerning is applied unknowingly and nobody catches it—in body copy. At text sizes, Optical kerning leaves things kind of tight overall and otherwise just slightly off.

How do I set the kerning default to Metrics?

Picture 1

Open InDesign without any documents open. In the Character palette, set the kerning field to Metrics. All done.

Aren’t we making a lot of assumptions here?

Only a couple. One—that the fonts you use most are good. Two, that when you could potentially benefit from Optical kerning, that you’ll know to switch over from your default.

That’s it. Catch Using Type here Thursdays.


  1. Paramjeet
    Posted September 13, 2013 at 12:36 AM | Permalink

    Hi David,
    Good tip to make metrics option default in Indesign.

    Just curious to know is that, why spacing between ligatures doesn’t change when we change their setting from metrics to optical or zero. Although they are two separate characters or glyphs. For example “fi” are two separate glyphs or “ffi” are three separate glyphs.


  2. Posted September 13, 2013 at 7:39 AM | Permalink

    Kerning doesn’t change the space between the characters in a ligature because even though for instance represents two characters, it’s still a single glyph, taking up one slot by itself in the glyph palette.

  3. Posted September 14, 2013 at 2:38 AM | Permalink

    Good tutorial!

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