What is 11 23mm on aps c in full frame?

11-23mm on APS-C gives the view of 16-34mm on full frame.

The same view on every common format:

• Medium format (44 x 33): 21-44mm
• Full frame: 16-34mm
• APS-C (yours): 11-23mm
• APS-C (Canon): 10-22mm
• Micro Four Thirds: 8.2-17mm
• 1-inch: 6.1-13mm
• 1/1.3-inch: 4.6-9.6mm
• 1/1.7-inch: 3.6-7.5mm
• 1/2.3-inch: 2.9-6.2mm

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.