Objective: To evaluate the degree to which the height, width, and cross-section of rectangular and square orthodontic archwires affect the play between the archwires and the bracket slot. Materials and Methods: The stated measurements (height and width) of 43 archwires from six different manufacturers were compared with real values obtained using a digital gauge. The curvature (radius) of the edge bevels was also measured to calculate the play within the slot, and this measurement was compared with the ideal value. Results: The real height and width of the archwires differed from those stated by the manufacturers, falling within the range 26.47% and +5.10%. The curvature of each bevel on each archwire cross-section was shown to differ, and consequently increased the real play between the archwire and slot with respect to the ideal to different degrees. Conclusions: The archwire-slot play was greater than the ideal for each archwire considered, inevitably leading to a loss of information within the system. (Angle Orthod. 2015;85:848-858.)