Expanded Preview Bounds

Yesterday, while working on a project I noticed what I thought was unexpected behavior in Adobe Illustrator when applying a stroke to a path. Surprisingly, the stroke weight changed width of the path object I had applied it to, which, in as much as I can recall, has never been the expected behavior. I spend a lot of time using Illustrator so this initially seemed like a bug or maybe related to corrupted preferences.

Apparently not. Instead, it seems to be a feature, though I’m (still) unclear when it was introduced. This functionality is the kind I would notice immediately if it was changed based on how I use the software. But maybe somehow I did?

Adobe Illustrator CC 25.4.1 application preferences window
Adobe Illustrator CC 25.4.1 Preferences Window.

So after some searching and experiments I tracked down to the problem to an Illustrator preference called “Use Preview Bounds.” Essentially when this is enabled, Illustrator now includes the width of a stroke in the total width of a path. This is identical to behavior in InDesign, despite entirely inconsistent terminology and ways of managing this setting.

This is up there for me like when Adobe changed the default behavior of scaling objects as they did in Photoshop a few years ago. Seemingly random and totally maddening.

But now you know.