Gear shaping cutters are provided with top-relief and rake angles. As a result of this, the profile representing the cutting edge is modified. This paper deals with the method of obtaining the effective profile on the rack-type and pinion-type cutters for spur gears. Analysis of the effective profile shows that the effective profile of the rack-type cutter is actually a straight-sided tooth form with different pressure angle and tooth thickness at the reference (pitch) line. In the case of the pinion-type cutter, tooth thinning takes place and the effective profile could not be identified with any involute form. This paper also deals with the methods of correcting the cutter profile form so that profile close to the theoretical form can be obtained on grinding the rake face. This approach would be quite useful to the designers and manufacturers of the shaping cutters. © 1983, Institution of Mechanical Engineers. All rights reserved.