What is 200 600mm on aps c in full frame?

200-600mm on APS-C gives the view of 300-900mm on full frame.

The same view on every common format:

• Medium format (44 x 33): 380-1139mm
• Full frame: 300-900mm
• APS-C (yours): 200-600mm
• APS-C (Canon): 188-562mm
• Micro Four Thirds: 150-450mm
• 1-inch: 111-333mm
• 1/1.3-inch: 83-250mm
• 1/1.7-inch: 65-196mm
• 1/2.3-inch: 54-161mm

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.