What is 80 400mm on aps c in full frame?

80-400mm on APS-C gives the view of 120-600mm on full frame.

The same view on every common format:

• Medium format (44 x 33): 152-759mm
• Full frame: 120-600mm
• APS-C (yours): 80-400mm
• APS-C (Canon): 75-375mm
• Micro Four Thirds: 60-300mm
• 1-inch: 44-222mm
• 1/1.3-inch: 33-167mm
• 1/1.7-inch: 26-130mm
• 1/2.3-inch: 21-107mm

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.