Yes. Grammarly launched an AI writing detector in 2023 and updated it in 2024. It is included with Grammarly Premium and is available in a limited free preview. It is a serviceable tool for its intended audience, which is business writers, and a less appropriate choice for classroom accountability decisions.
Quick Answer
Yes, Grammarly detects AI. The tool ships with Premium and offers a limited free preview. It returns a single percentage rather than a sentence-level breakdown. Accuracy claims are aggregate and not subgroup-disclosed. Fine for business writing. Not the pick we would centralize on for a classroom.
The full picture is worth the six-minute read, because the same company selling the AI writing assistant is selling the AI detector, and the overlap changes how the tool should be used.
The Short Answer
The interesting part is not whether Grammarly detects AI. It does. The interesting part is that Grammarly also sells one of the most popular AI writing assistants on the market, which puts the company on both sides of the same problem.
Grammarly now sells both the tool that produces AI-tinged prose and the tool that flags it.
The Working Educators editors
What Grammarly’s AI Detector Does
The Grammarly AI Detector analyzes a pasted document and reports a percentage estimate of how much of the text is likely AI-generated. The tool integrates with Grammarly’s wider writing platform, so a Premium user can move from grammar suggestions to an AI check without switching apps.
The output is a single confidence number rather than a sentence-by-sentence breakdown. That is a workflow decision that suits marketing and business writing, where the question is often “did a contractor use ChatGPT” rather than “which passages did a student generate.”
The Vendor’s Accuracy Claims
Grammarly reports that its detector was trained on a mix of human and AI text spanning multiple models. It publishes an aggregate accuracy claim on the product page. It does not, to our knowledge, publish subgroup false-positive rates for non-native English writers, academic populations, or specific model families.
This is the same disclosure gap that runs through most of the detector market. It is a bigger concern for classrooms than for corporate contexts because the Liang et al. (2023) finding on non-native writers is an active civil rights problem in a school setting.
The Grammarly-Go Irony
Grammarly launched “Grammarly Go,” a generative writing assistant, in the same season it launched the AI detector. The company’s product line now sells both the tool that produces AI-tinged prose and the tool that flags it.
That is not necessarily hypocritical. Businesses reasonably want both. A marketing lead can use the writing assistant for a first draft and the detector to make sure a client submission is not visibly machine-authored. But in an academic setting, the same overlap gets awkward. A student who used Grammarly’s free tier for grammar fixes has to hope the fix pass did not reshape their prose into something the detector will flag.
When It Fits in a Classroom Context
For teachers already paying for Grammarly Premium for their own writing, running a spot check through the AI detector is a reasonable low-cost signal. It should not be the basis of an accusation on its own. See our evaluation guide for the questions we would ask before treating any detector as evidence. Grammarly's plagiarism check is covered separately in our free plagiarism checker comparison.
For institutions choosing a primary academic AI detector, Grammarly is not the tool we would centralize on. Vendors with published methodology papers and academic-population calibration are the more defensible pick, and our 2026 teacher guide lays out the shortlist. For the teacher-first option we cover in that piece, see Proofademic.
Frequently Asked Questions
Is the Grammarly AI detector free?▼
There is a limited free preview. Full access is bundled with Grammarly Premium.
Does it work inside Google Docs and Microsoft Word?▼
Grammarly’s wider platform integrates with both. The AI detector is generally used from the web app.
How accurate is it?▼
Grammarly reports aggregate accuracy on its product page. Independent testing puts it in the middle of the pack. There is no published subgroup false-positive number for non-native writers.
Should teachers accuse students based on Grammarly output?▼
No detector should be the sole basis of an accusation. Grammarly is no exception.
Is Grammarly Go the same as ChatGPT?▼
It is Grammarly’s generative writing assistant, built on large language model technology. Different product, similar category.
The Bottom Line
Grammarly detects AI competently for its target audience. That audience is business writers who need a fast confidence signal, not teachers building an academic integrity case.
For classrooms, we would use it as one input among several and centralize on a detector with published academic-population calibration for anything that could end up in a conduct meeting.
