You asked
What is 100 300mm on micro four thirds in full frame?
100-300mm on Micro Four Thirds gives the view of 200-600mm on full frame.
The same view on every common format:
- Medium format (44 x 33): 253-759mm
- Full frame: 200-600mm
- APS-C: 133-400mm
- APS-C (Canon): 125-375mm
- Micro Four Thirds (yours): 100-300mm
- 1-inch: 74-222mm
- 1/1.3-inch: 56-167mm
- 1/1.7-inch: 43-130mm
- 1/2.3-inch: 36-107mm
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.