The Braille Volume Bound: Why a Textbook Becomes a Shelf, and What Fits in a Schoolbag

Braille is spacious. From the standard cell geometry, this paper computes characters per page, the page count of a stated 400,000-character textbook in Braille, its thickness and its mass. The bound explains, in numbers, why Braille textbooks arrive as multi-volume sets and why a pupil cannot carry a term's reading in one bag. Any access plan that ignores the volume bound will fail at the school gate; refreshable displays and audio are priced in the discussion against this bound. Computed results: chars_per_page = 1148, braille_pages = 348, thickness_m = 0.09, mass_kg = 4.2, volumes_of_100_pages = 3.5. Every number in this paper is produced by the accompanying script `compute.py`. SIMULATED, NOT MEASURED.