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?
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.
Structured fields
{
"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
Rights
| component | license | hosting | redistribution | modification | training | Evidence and notes |
|---|---|---|---|---|---|---|
| documentation | unknown | permitted | permitted | unknown | unknown | Applies to this original summary only, not to the cited sources. |