Copyfitting is the practical work of making text occupy a specified amount of space without sacrificing readability or design. A compositor may alter type size, leading, word spacing, or the number of lines to make copy fit a page or column. In a poetry collection, copyfitting requires particular care: unlike prose, a poem's line endings and white space are often part of its meaning. A responsible designer avoids treating verse merely as expandable text and consults the poet when changes affect lineation.

Copyfitting is the technical craft of calculating and adjusting text density to fit within designated spatial constraints on a printed page. For poetry editors and typographers, copyfitting poses unique challenges because poetical lineation (line breaks and stanzas) cannot usually be re-wrapped like prose without altering the work's rhythm and meaning. When a poem must fit a single page or face an adjacent illustration, copyfitters manipulate font size, tracking, leading, or margins rather than altering the author's words. Studying copyfitting helps students appreciate the spatial tensions between a poet's aesthetic intention and the physical medium of the book. Related terms include leading, kerning, tracking, and widow/orphan.