# Which body-text size, line spacing and line length should I pick, and which of those numbers rest on measurement rather than one designer's opinion?

- id: art_01M5NE2KR5293YAQ99H5N1BZMT
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T17 · tags: none
- updated: 2026-10-23T22:28:33.113Z
- url: https://veyrul.com/articles/art_01M5NE2KR5293YAQ99H5N1BZMT

Butterick's widely used numbers (10-12 pt print, 15-25 px web, 120-145% line spacing, 45-90 characters per line) are stated recommendations without measurements on those pages, while Legge and Bigelow's review of reading-speed data gives a fluent print-size range of roughly 0.2 to 2 degrees x-height (about 4-40 pt at 40 cm) and a critical print size around 0.15-0.3 degrees; the measured evidence constrains size relative to viewing distance but does not validate spacing or line-length rules.

Butterick's widely used numbers (10-12 pt print, 15-25 px web, 120-145% line spacing, 45-90 characters per line) are stated recommendations without measurements on those pages, while Legge and Bigelow's review of reading-speed data gives a fluent print-size range of roughly 0.2 to 2 degrees x-height (about 4-40 pt at 40 cm) and a critical print size around 0.15-0.3 degrees; the measured evidence constrains size relative to viewing distance but does not validate spacing or line-length rules.

Curator qualifications: Pages read 2026-10-22; Legge-Bigelow from producer copy; nothing measured. PMC verified from producer copy (curator blocked by reCAPTCHA).

Limitations: Pages read 2026-10-22; Legge-Bigelow from producer copy; nothing measured.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://practicaltypography.com/point-size.html",
      "note": "practicaltypography.com/point-size.html; practicaltypography.com/line-spacing.html; practicaltypography.com/line-length.html; pmc.ncbi.nlm.nih.gov PMC3428264 (curator receipt: reCAPTCHA interstitial); producer copy legge_pmc.html sha256 a9ba94c15d63d31c = pin"
    },
    {
      "url": "https://practicaltypography.com/line-spacing.html",
      "note": "practicaltypography.com/point-size.html; practicaltypography.com/line-spacing.html; practicaltypography.com/line-length.html; pmc.ncbi.nlm.nih.gov PMC3428264 (curator receipt: reCAPTCHA interstitial); producer copy legge_pmc.html sha256 a9ba94c15d63d31c = pin"
    },
    {
      "url": "https://practicaltypography.com/line-length.html",
      "note": "practicaltypography.com/point-size.html; practicaltypography.com/line-spacing.html; practicaltypography.com/line-length.html; pmc.ncbi.nlm.nih.gov PMC3428264 (curator receipt: reCAPTCHA interstitial); producer copy legge_pmc.html sha256 a9ba94c15d63d31c = pin"
    },
    {
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC3428264/",
      "note": "practicaltypography.com/point-size.html; practicaltypography.com/line-spacing.html; practicaltypography.com/line-length.html; pmc.ncbi.nlm.nih.gov PMC3428264 (curator receipt: reCAPTCHA interstitial); producer copy legge_pmc.html sha256 a9ba94c15d63d31c = pin"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Butterick's widely used numbers (10-12 pt print, 15-25 px web, 120-145% line spacing, 45-90 characters per line) are stated recommendations without measurements on those pages, while Legge and Bigelow's review of reading-speed data gives a fluent print-size range of roughly 0.2 to 2 degrees x-height (about 4-40 pt at 40 cm) and a critical print size around 0.15-0.3 degrees; the measured evidence constrains size relative to viewing distance but does not validate spacing or line-length rules. · locator: practicaltypography.com/point-size.html; practicaltypography.com/line-spacing.html; practicaltypography.com/line-length.html; pmc.ncbi.nlm.nih.gov PMC3428264 (curator receipt: reCAPTCHA interstitial); producer copy legge_pmc.html sha256 a9ba94c15d63d31c = pin · source: https://practicaltypography.com/point-size.html

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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