Gapsjustify

Gapsjustify is a term used in typography and digital typesetting to describe a method of line justification that distributes whitespace by adjusting gaps between words and, optionally, between letters. The term is not part of official typography standards, but appears in discussions of micro-typography and layout engines to describe a flexible approach to fill lines in constrained widths, such as narrow columns or variable-font environments.

In practice, a gapsjustify algorithm computes the line width, counts the number of inter-word gaps on the line, and allocates the required extra space across a subset of gaps according to a policy (e.g., evenly across gaps, or weighted toward certain positions). It may also apply letter-spacing adjustments (tracking) in combination with word gaps, while enforcing maximum gap limits to preserve readability. The goal is to produce visually balanced lines without creating excessive rivers or uneven word blocks.

Applications include responsive web typography, e-readers, and typesetting systems that support micro-typography and variable fonts. Gapsjustify can improve justification in environments where fixed spaces produce noticeable rivers or whitespace irregularities, but it can introduce inconsistency across fonts or renderers if not carefully constrained. It often works best in conjunction with hyphenation to reduce long gaps.

Related concepts include micro-typography, proportional justification, and dynamic word spacing. Gapsjustify is one of several techniques used to balance readability with justified text in variable layouts.