The crop factor of Canon's APS-C sensors is 1.62. The value is different from other APS-C sensors from other brands. In this case:
Find the dimensions of the sensor:
Width = 22.3 mm;
Height = 14.9 mm.
Find the diagonal with Pythagora's theorem:
d = sqrt(222² + 14.8²) = 26.68
Divide the length of the diagonal of a full-frame sensor (43.26 mm) by the previous result:
CF = diagonal full-frame/diagonal crop sensor = 43.26/26.68 = 1.62
The result is the crop factor of an APS-C sensor by Canon. Read more