Computed tomography is used to assess whether ideal femoral component size in knee arthroplasty can be made more accurately. Ideal femoral component size was measured on radiography, computed tomography, and by direct measurement of 20 cadaver femora and analyzed statistically. There was no significance between the tomographically anticipated ideal femoral component size and ideal femoral size values (Wilcoxon W 388.5; p 0.565). There was difference between radiographically anticipated ideal femoral size and ideal femoral size values (Wilcoxon W 324.5; p 0.020). Anticipating the ideal femoral size can be made more precisely with computed tomography than radiographs in cadaver femora. Anticipating the ideal femoral component size by computed tomography may solve the problems in "in-between sizes." Future total knee designs may be manufactured in more anatomic sizes.