Print ComparisonsBy: Carmen Willings
teachingvisuallyimpaired.com Updated June 14, 2025 I frequently use environmental print comparisons to help team members understand the relationship between a student's near visual acuity and accessible font sizes. This is especially helpful when discussing accommodations for students with low vision.
It’s important to note: although a student may be able to see a smaller font (their visual threshold), this does not mean it is a functional or efficient size for reading sustained text. The most appropriate font size is the smallest one the student can read easily, accurately, and fluently over extended periods.
Near Vision Snellen Test Chart with Environmental Print ComparisonsThe following chart correlates Snellen acuity with typical print sizes and real-world examples:
Source: Low Vision Clinic, N.C. Memorial Hospital, Dept. of Ophthalmology, UNC School of Medicine, Chapel Hill, NC.
Functional Distance Acuity Approximations (at 20 feet)This table compares gross object size and minimum detail size with approximate Snellen acuity at a standard viewing distance of 20 feet:
Approximating Functional Visual Acuity (for Nonverbal Students)For students who are nonverbal or cannot participate in standardized visual acuity testing, functional acuity may be approximated by comparing the size of the object a student can recognize and the distance from which it is viewed:
Source: Topor, I. (2004). Early Intervention Training Center for Infants and Toddlers With Visual Impairments, UNC-CH.
Tools for Estimating Font SizeTypesetter Ruler (e.g., C-Thru Flexible Typesetter’s Ruler)
Typometer
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