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.

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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.

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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!

  4. Posted May 9, 2014 at 12:41 PM | Permalink

    Once upon a time, optical was better than metric. Today we can build in sophisticated algorithms into our software to make tracking/kerning adjustments and account for every conceivable letter combination (at least we have to hope that quality type designers are actually doing this). From the wayback machine: When I set type in the 80’s, we had to memorize all the letter combinations for kerning and manually insert special keystrokes to force the Compugraphic PhotoTypesetter to add or subtract space between characters. “those were the days” TGIF. Still, one size does not fit all–size of type and character width are huge factors in spacing decisions, whether metric or optical or “0”.

  5. Posted May 9, 2014 at 12:58 PM | Permalink

    Thanks Beth. Optical is better than Metric under certain circumstances, (and it definitely sounds better, doesn’t it?) however I can’t recommend Optical kerning as a default unless you’re working primarily with poorly-spaced digital type. Even then, my recommendation is to use better type, or type more suited to the target size, before relying on an algorithm based on a spacing theory to redo the type designer’s work.
    Those who hand-set metal type today still memorize kerning pairs, though the list of kerns is considerably shorter. Or is it? About how many pairs per font were you required to keep track of back then?

  6. Posted May 13, 2014 at 2:29 PM | Permalink

    The only way to adjust kerning in hand set metal type was using either a file (negative) or special extremely thin foil (positive). Only very dedicated pressmen would do that…

  7. Posted May 13, 2014 at 2:41 PM | Permalink

    That’s right Bert. Sorry, my question above was directed to Beth regarding hand-coding kerns on the Compugraphic system she used. In commenting on hand-set metal type, I was referring mainly to negative kerns where both letters are cast on a single body, e.g. To or Ta.

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