What is 20 50mm on canon aps c in full frame?

20-50mm on APS-C (Canon) gives the view of 32-80mm on full frame.

The same view on every common format:

• Medium format (44 x 33): 41-101mm
• Full frame: 32-80mm
• APS-C: 21-53mm
• APS-C (Canon) (yours): 20-50mm
• Micro Four Thirds: 16-40mm
• 1-inch: 12-30mm
• 1/1.3-inch: 8.9-22mm
• 1/1.7-inch: 7-17mm
• 1/2.3-inch: 5.7-14mm

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.