You asked
What is 25 50mm on micro four thirds in full frame?
25-50mm on Micro Four Thirds gives the view of 50-100mm on full frame.
The same view on every common format:
- Medium format (44 x 33): 63-127mm
- Full frame: 50-100mm
- APS-C: 33-67mm
- APS-C (Canon): 31-62mm
- Micro Four Thirds (yours): 25-50mm
- 1-inch: 19-37mm
- 1/1.3-inch: 14-28mm
- 1/1.7-inch: 11-22mm
- 1/2.3-inch: 8.9-18mm
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.