You can choose a precise measurement (either UPM or Ascender-to-Descender height), set some settings, and it will do the rest.
Enter your desired measurement here, measured in units.
This is what your measurement will correspond to. You can scale based on UPM, or your ascender-to-descender height. If you scale your UPM, everything (chosen to be scaled) will be scaled proportionately. If you scale your Ascender-to-Descender height, you'll have the option on how/whether UPM is changed...
These options are only available when Asc-Desc Height is enabled:
Scale the UPM proportionately to how you're scaling the ascender-to-descender height is being scaled. This will ensure the relationship between your font dimensions and your UPM is maintained.
This will snap the UPM to match the Unit measurement provided and match the distance between your ascender and descender.
This will leave UPM unaffected while everything else scales around it. This is useful, for instance, if you've already got your UPM where you want it, but your glyphs/font dimensions are too small/big.
These are things you can choose to scale along with everything else. Usually it’s a good idea to leave all of these checked.
Note: Components themselves will not be scaled, as this would scale things twice. However, it is recommended you scale the Component Offset (i.e. the positioning of the components). This will most likely lead to the desired results.
When you scale drawings, there may be float numbers that no longer fit the grid you're working on. If you'd like to leave them float for now, choose Don’t Round. If you'd like your final drawings to be shimmied a bit to fit a 1-unit grid, choose 1 Unit.
Choose which layers you’d like to scale, either just the default layer (usually named “foreground”), or all layers.
Choose which fonts you’d like to scale, either just the front-most CurrentFont, or all open fonts.
Choose whether you’d like to scale the font in-place, or whether you'd like Slinky to make a copy first and then scale.
Note: If you scale the font in-place, just remember that it’s difficult to Undo this action. Be sure your work is saved before clicking Scale. In case the wrong move is made here, you can then close and reopen the UFO. It might be a good idea to try out “As New Font” and check the results before committing the same settings to the actual UFO in question.