Design Nomenclature / Type

Optical spacing

Also called optical kerning, fitting

Fitting letters so the white between them looks even rather than measures even — a straight-sided n takes more space beside it than a round o, which takes more than a diagonal A. The principle behind a type designer's sidebearings, and behind InDesign's Optical kerning, which derives spacing from outlines instead of the font's kern pairs.

The string noAv set large, each letter on its own body, with the three gaps between the letters tinted from baseline to x-height and measured in em beneath. n to o, flat beside round, is 0.058 em. o to A, round beside diagonal, is 0.015 em. A to v, diagonal beside diagonal, is −0.032 em: the outlines cross their own bodies, so the gap is negative and its tint is darker. Three measured spaces an order apart, fitted by Georgia to read as one.

In practice

Optical kerning overrides a good font's own pairs, which are usually better. It earns its keep on faces with poor or absent kerning data, and on mixed-face runs where no pairs exist.

Not to be confused with

How this term connects

CounterKerningOvershootSidebearingTrackingOptical spacing
Related Confused with