Does Turnitin Draft Coach detect AI?
No
No. Draft Coach runs three checks for students: similarity, citations and grammar. The AI writing report is not one of them.
How it works
Draft Coach is an add-on that sits inside Google Docs and Word on the web while you are still writing. Its similarity check compares the draft against Turnitin's sources and returns a report only you can see, and you get three of those per document; the citation and grammar checks are unlimited. The AI writing indicator belongs to the instructor's side of the product, so nothing you do in Draft Coach produces one or previews one.
The part people miss
Checking a draft here does not put it into Turnitin's repository, so it will not match against itself when you submit for real. The feature list is Turnitin's to change, and what is described here is what its Draft Coach FAQ documented in September 2026. Sites that promise you a Turnitin AI percentage before submission are running a different detector entirely.
Does the similarity score include AI writing?
No. Similarity and AI writing are two systems producing two numbers, and neither feeds the other. Similarity counts overlap with documents Turnitin has indexed. The AI indicator estimates how much of your qualifying prose resembles machine writing.
This is why generated text often shows 0% similarity. A paragraph written for you on request is usually new wording, so it matches nothing, while the AI indicator climbs. The reverse case is a heavily quoted essay: high similarity, no AI flag at all. The one case where both move together is generated text that happens to reproduce something already in the index, and even then the two numbers were calculated independently.
Flagged for something you wrote yourself?
There is a right order to handle it in, and editing the document first destroys your best evidence.