Fifty-five photographs of a standard shoe print, excluding scale, were taken, and three approaches based on mathematical theorems and ratios were used to determine shoe size. The ratio method comparing shoe print to a reference object was a straightforward approach to measuring the length of shoe prints photographed without a scale. The grid method expressed the heel and toe as being two points on a grid. The triangle method employed a line to bisect the shoe print through its heel and toe and treated the bisecting line as a segment of the hypotenuse of a right triangle. For all methods, measurements of objects captured in photograph backgrounds were used to convert photographic measurements of shoe prints into whatever units were used to measure the background objects. In general, mathematical calculation results fell within an acceptable margin of error. Two areas of inconsistency, however, persisted throughout the study. One involved the necessity to estimate fractions of grid blocks in the grid method. The other involved the process by which judgments were applied to identify the photographic viewpoint as vertical or near vertical; these judgments affected the choice of converged line to serve distortion control. 4 references, 2 tables.