 Natural line width

The natural line width is the width a candidate line occupies before any stretch or shrink of its typesetting glue. In a simple horizontal model with fixed typesetting box widths $w_i$ and nominal glue widths $g_j$,Additional fixed positioning adjustments must be included when the model contains them. If a discretionary break inserts a hyphen at the chosen endpoint, its width belongs to that candidate's natural width.

For example, boxes of widths 8, 6 and 10 and two nominal gaps of width 3 give $N=30$. To reach a typesetting line width $W=32$, the glue must absorb $W-N=2$. A total finite stretch coefficient $S=4$ gives line adjustment ratio $r=(W-N)/S=1/2$. The typesetting glue diagram shows the resulting adjustment.

Computing the natural width first separates the dimensions of the selected material from its later spacing adjustment. This also lets a line breaking algorithm compare several endpoints before committing to a final line. In the fixed-space model, prefix sums make repeated width calculations efficient.