Skill Wiki
Line Height Readability
Optimal line-height for body prose is in the 1.5–1.7 range (unitless multiplier of font-size), with editorial / long-form content tending toward 1.6–1.7 and dense UI body text tending toward 1.4–1.5; values below 1.…
$ prime install @community/fact-line-height-readabilityProjection
Always in _index.xml · the agent never has to ask for this.
LineHeightReadability [fact] v1.0.0
Body line-height between 1.5 and 1.7 produces the most legible reading rhythm for prose; tighter (≤1.3) crowds ascenders into descenders, looser (≥1.8) breaks the reader's vertical tracking between lines.
Optimal line-height for body prose is in the 1.5–1.7 range (unitless multiplier of font-size), with editorial / long-form content tending toward 1.6–1.7 and dense UI body text tending toward 1.4–1.5; values below 1.3 cause ascender / descender collisions and values above 1.8 break inter-line continuity.
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LineHeightReadability [fact] v1.0.0
Body line-height between 1.5 and 1.7 produces the most legible reading rhythm for prose; tighter (≤1.3) crowds ascenders into descenders, looser (≥1.8) breaks the reader's vertical tracking between lines.
Optimal line-height for body prose is in the 1.5–1.7 range (unitless multiplier of font-size), with editorial / long-form content tending toward 1.6–1.7 and dense UI body text tending toward 1.4–1.5; values below 1.3 cause ascender / descender collisions and values above 1.8 break inter-line continuity.
Confidence
strong
Applies To
- body / paragraph CSS line-height
- type-scale design (each step gets matched line-height)
- WCAG 2.2 text-spacing compliance (SC 1.4.12)
- responsive type: line-height may tighten slightly at larger font-sizes
Quantitative
- Body Prose Range: 1.5–1.7
- Editorial Target: 1.6–1.7
- Dense Ui Target: 1.4–1.5
- Headline Target: 1.1–1.3 (tighter — display sizes need less leading)
- Wcag Floor: 1.5 (SC 1.4.12, minimum for paragraphs to support user style overrides)
Counter Conditions
- CJK / Indic / Arabic typography has different optical needs — ranges shift.
- Tight UI density (Linear, Notion sidebars) may legitimately use 1.3–1.4 line-height for compact lists.
- Display-size headlines need lower multipliers (1.0–1.2) because the absolute leading is already large.
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LineHeightReadability [fact] v1.0.0
Body line-height between 1.5 and 1.7 produces the most legible reading rhythm for prose; tighter (≤1.3) crowds ascenders into descenders, looser (≥1.8) breaks the reader's vertical tracking between lines.
Optimal line-height for body prose is in the 1.5–1.7 range (unitless multiplier of font-size), with editorial / long-form content tending toward 1.6–1.7 and dense UI body text tending toward 1.4–1.5; values below 1.3 cause ascender / descender collisions and values above 1.8 break inter-line continuity.
Confidence
strong
Applies To
- body / paragraph CSS line-height
- type-scale design (each step gets matched line-height)
- WCAG 2.2 text-spacing compliance (SC 1.4.12)
- responsive type: line-height may tighten slightly at larger font-sizes
Quantitative
- Body Prose Range: 1.5–1.7
- Editorial Target: 1.6–1.7
- Dense Ui Target: 1.4–1.5
- Headline Target: 1.1–1.3 (tighter — display sizes need less leading)
- Wcag Floor: 1.5 (SC 1.4.12, minimum for paragraphs to support user style overrides)
Counter Conditions
- CJK / Indic / Arabic typography has different optical needs — ranges shift.
- Tight UI density (Linear, Notion sidebars) may legitimately use 1.3–1.4 line-height for compact lists.
- Display-size headlines need lower multipliers (1.0–1.2) because the absolute leading is already large.
Sources
Confidence
strong
Source
- Bringhurst, 'The Elements of Typographic Style' — chapter on leading
- WCAG 2.2 SC 1.4.12 Text Spacing — line-height ≥ 1.5 within paragraphs
- Smashing Magazine, 'Setting Optimal Line Length' / line-height research
- Google Material — Type scale line-height tokens
Applies To
- body / paragraph CSS line-height
- type-scale design (each step gets matched line-height)
- WCAG 2.2 text-spacing compliance (SC 1.4.12)
- responsive type: line-height may tighten slightly at larger font-sizes
Quantitative
- Body Prose Range: 1.5–1.7
- Editorial Target: 1.6–1.7
- Dense Ui Target: 1.4–1.5
- Headline Target: 1.1–1.3 (tighter — display sizes need less leading)
- Wcag Floor: 1.5 (SC 1.4.12, minimum for paragraphs to support user style overrides)
Counter Conditions
- CJK / Indic / Arabic typography has different optical needs — ranges shift.
- Tight UI density (Linear, Notion sidebars) may legitimately use 1.3–1.4 line-height for compact lists.
- Display-size headlines need lower multipliers (1.0–1.2) because the absolute leading is already large.
Source
prime-system/examples/frontend-design/primes/compiled/@community/fact-line-height-readability/atom.yaml