Caesar, Commentaries on the Gallic War (first 10 chapters):

  • Character count (no spaces)
    • English: 10,544
    • Latin: 8,203
    • Latin is 78% length of English

Cicero, Ad Familiares (Book 1, Chapter 1)

  • Character count (no spaces)
    • English: 3,271
    • Latin: 2,369
    • Latin is 72% length of English

Newton, Philosophiae Naturalis Principia Mathematica (Book 1, Chapter 1, First 3 lemmata)

    • English: 2,295
    • Latin: 1,959
    • Latin is 85% length of English

Tacitus, Germania (first 10 chapters):

  • Character count (no spaces)
    • English: 9,640
    • Latin: 7,614
    • Latin is 79% length of English

Varro, On Agriculture (first 10 chapters):

  • Character count (no spaces)
    • English: 33,289
    • Latin: 27,064
    • Latin is 81% length of English

So overall, the Latin pages are on average (mean) 79% the length of the English pages.

(78+72+85+79+81) divided by 5 = 79.