Words that sound similar tend to have similar meanings, at a distributed, sub-symbolic level (Monaghan, Shillcock, Christiansen, & Kirby, 2014). We extend this paradigm for measuring systematicity to letters and their canonical pronunciations. We confirm that orthographies that were consciously constructed to be systematic (Korean and two shorthand writing systems) yield significant correlations between visual distances between characters and the corresponding phonological distances between canonical pronunciations. We then extend the approach to Arabic, Hebrew, and English and show that letters that look similar tend to sound similar in their canonical pronunciations. We indicate some of the implications for education, and for understanding typical and atypical reading. By using different visual distance metrics we distinguish between symbol-based (Korean, shorthand) and effort-based (Arabic, Hebrew, English) grapho-phonemic systematicity. We reinterpret existing demonstrations of phono-semantic systematicity in terms of cognitive effort.