This study investigated students' with visual impairment concepts about linear size and scale. Specifically the study examined the accuracy of students' concepts over many orders of magnitude as well as experiences students have had in and out-of-school learning about size and scale. The results of assessments of 17 students with visual impairment were compared to those of students with normal sight. The study showed that students with visual impairment were most accurate for measurements in the human scale and were least accurate with very large and very small scales that cannot be directly experienced. However, when compared to students with normal sight, students with visual impairment were more accurate at large and small scales than their normally sighted peers. (Contains 1 table and 6 figures.)