Chrome 147 quietly downloads a 4GB AI model — here's how to stop it
If you've noticed your storage shrinking by about 4GB after updating Chrome, you're not imagining it. Google's Chrome 147, released between April 20–29, 2026, silently downloads a file called weights.bin — the core of its Gemini Nano AI model — onto your device with no prompt, no consent dialog, and no obvious opt-out. Privacy researcher Alexander Hanff documented the behavior in forensic detail, and the findings have since been confirmed by multiple outlets.
What's actually happening
Gemini Nano powers several on-device AI features in Chrome: scam detection, "Help me write," and advanced autofill. Google's rationale is that running the model locally keeps your data off its servers. The file lands deep inside your browser profile, in a folder called OptGuideOnDeviceModel, and it takes up roughly 4GB of disk space.
The catch: deleting the file doesn't fix it. As long as Chrome's AI features remain enabled, the browser re-downloads weights.bin the next time it starts. It's persistent by design. The only way to stop it permanently is to go into Chrome's settings and disable On-Device AI entirely — only then will manually removing the OptGuideOnDeviceModel folder actually stick.
For anyone on a high-capacity drive, 4GB is an irritant. For budget laptops, older machines, or devices with limited storage, it can be a genuine problem. Google didn't notify users, didn't surface the storage requirement when enabling AI features, and doesn't offer a clear choice between local and cloud-based processing.
The legal and privacy angle
That Privacy Guy – Chrome forensic analysis argues the deployment may violate ePrivacy Directive Article 5(3) and GDPR Articles 5(1) and 25 — rules that require explicit consent before writing software to a user's device. Hanff also estimates the mass rollout across over a billion devices could generate 6,000–60,000 tonnes of CO2 equivalent in network transmission alone, though Tom's Hardware – regulatory skepticism notes those environmental figures rely on disputed assumptions.
No enforcement action has been initiated yet, and Google has not issued a formal response to the privacy allegations. In the US, neither CCPA nor any federal rule explicitly governs AI model installs pushed via browser updates — meaning there's currently no clear legal backstop for American users.
How to remove it
1. Open `chrome://flags` and disable the Optimization Guide On Device Model flag. 2. In Chrome Settings, turn off On-Device AI under the AI section. 3. Delete the OptGuideOnDeviceModel folder from your Chrome profile directory.
The visible "AI Mode" button in Chrome's address bar is separate — it routes queries to Google's cloud servers, not to Gemini Nano. Disabling on-device AI won't remove that button.
Microsoft and Apple are pushing local AI models into their own products too, so Chrome's approach may become an industry template. Whether users get a say in that is still an open question.