What is 90mm on canon aps c in full frame?

90mm on APS-C (Canon) gives the view of 144mm on full frame.

The same view on every common format:

• Medium format (44 x 33): 182mm
• Full frame: 144mm
• APS-C: 96mm
• APS-C (Canon) (yours): 90mm
• Micro Four Thirds: 72mm
• 1-inch: 53mm
• 1/1.3-inch: 40mm
• 1/1.7-inch: 31mm
• 1/2.3-inch: 26mm

Crop factors are by the sensor diagonal, rounded as they're usually quoted; a format with a different shape (4:3 against 3:2) frames a little differently across the width. More in the focal length converter.

Computed from the sensor sizes, not written by a model.