Don’t forget that the zoom level shown in an editor such as Photolab is with respect to the screen’s pixel density and size, not the camera sensor sizes such as "“Full Frame”, APC, 4/3rds, etc.
“Crop factor” when referring to camera sensor sizes is different than cropping in an editing program.
Your comments suggest you are calculating “Crop factor” for comparing various camera sensor sizes, such as “full frame”, APC, 4/3rds, etc.
When using optics to change “crop factor” affects both the apparent zoom (focal length) and the depth of field. When using an editing program to crop an image the apparent “zoom” changes, but the depth of field (what is in focus) does not. This impacts the final result.
Each brand of camera (and major revisions) have a slightly different size sensors, so if trying to be more than casually accurate, you will need to use exact sizes.
If you are trying to create a final image with specific dimensions such as a fixed number of pixels on each side or physical dimensions you can also “resize” an image or modify the “PPI” (pixels per inch).
If more info is desired, please share more specifics.