Luckily to clear up any self-bragging confusion, test scores and thus literacy, are standardized through tests (primarily written and distributed by McGraw-Hill, which was founded by Ghislaine Maxwell's [yes Epstein's Ghislaine Maxwell] Father.)
That totally normal fact aside, the general measurement is reading speed across age-appropriate 'Lexile' levels, which is an annoying complex metric assigned to various texts based on grammar, word count, word complexity, complexity of the plot(s), and kinda general vibe.
The Hobbit is 1000L, which is the middle of a 5th grade reading level. Pretty much any fifth grade student, theoretically, should be able to read The Hobbit with little to no trouble nor the need to look up additional words; at around 130 words per minute.
For some other fun examples, Twilight is 720L (3rd grade reading level), Robinson Crusoe is 1360L (at least 7th grade), The Lord of the Rings Trilogy ranges from 810-920L (4th grade reading level, so good brag) and War and Peace, shockingly, is only 1180L.