- Go to the Shape tool tab
2. From the Ratio drop-down menu, select the aspect ratio required or use the Unconstrained ratio, as desired. Note that the Original option maintains the aspect ratio of the initial capture.
N.B. As of Capture One 22 (15.3) your Aspect Ratio will be remembered on a per-variant basis. It is no longer a 'global' setting. You can change this in your preferences under Crop > Behavior as outlined below.
3. Drag a crop frame in the Viewer. Depending on your preference settings, there will be a semi-transparent mask over the area that is being cropped.
4. The orange numbers on the sides indicate the size of the cropped image.
How to change the size unit to px/in/cm/mm in the Crop tool?
5. To see the applied crop in its final form, select another cursor tool or press Enter.
Note: sometimes you can observe that Crop cannot change dimensions or is stuck at a particular crop setting, like here:
To avoid that, please make sure that your Scale is set to Fixed in the Export Format & Size:

Any other options would "lock" the crop setting, so it stays there unchanged or only works within a constrained space. This is going to unlock the Crop dimensions for you and let you dial the size of the crop you want to export with.