What Is Chrome’s 4GB Gemini Nano File and Why It’s There
If your Chrome storage space has suddenly grown, the culprit might be a 4GB file called weights.bin, tucked inside a folder named OptGuideOnDeviceModel. This file is a local copy of Google’s Gemini Nano model, a small large-language model that powers on-device AI features like scam detection, autofill suggestions, writing assistance, tab organization, and browsing helpers. Instead of sending everything to remote servers, Chrome can run some AI tasks directly on your machine using this model. That’s good for privacy in theory, but there’s a catch: many users never see a clear prompt telling them that a multi-gigabyte download is about to land on their drive. The install happens quietly in the background once certain AI features or websites that use Chrome’s on-device Gemini API are triggered, and it can appear at different times depending on your hardware and account.
How to Check Whether Gemini Nano Is on Your Computer
Before you delete AI files, you need to confirm whether the Gemini Nano model is actually present. The easiest way is to inspect your Chrome data directory and look for the OptGuideOnDeviceModel folder that contains weights.bin. On many systems, this folder lives somewhere under your user profile’s Chrome application support or configuration path. If you’re comfortable with command-line tools, you can also search for very large files inside the Chrome directory; for example, by scanning for files larger than 1GB and checking whether weights.bin appears in the results. Remember that the model isn’t installed for everyone. Chrome only downloads it when certain conditions are met, including your hardware capability, enabled account features, and whether you’ve visited sites that call Chrome’s on-device AI APIs. If you don’t see the folder or file after searching, Chrome likely hasn’t stored the Gemini Nano model on your device yet.
Step-by-Step: Delete the 4GB Model and Free Up Disk Space
Once you’ve located weights.bin, you can reclaim that 4GB and free up disk space in a few minutes. First, close all Chrome windows so the browser releases any lock on its data files. Next, navigate to the OptGuideOnDeviceModel directory in your Chrome profile and delete the weights.bin file. This removes the local Gemini Nano model and immediately recovers the occupied storage. However, deleting the file alone isn’t enough if Chrome still thinks it should use on-device AI. With AI features active, Chrome may silently re-download the same file later. That’s why this step is best combined with changing Chrome settings so the browser stops requesting the model at all. If you don’t adjust those options, you’ll likely see the file reappear after some time, eating the same chunk of storage space all over again.
Turn Off On-Device AI in Chrome Settings to Stop It Coming Back
To permanently reclaim Chrome storage space from Gemini Nano, you need to switch off the local AI feature in Chrome settings. In the address bar, type chrome://flags and press Enter to open Chrome’s experimental settings page. Use the search box to find the entry named optimization-guide-on-device-model. Change its value from Default or Enabled to Disabled. After you’ve done this, restart Chrome so the new setting takes effect. When the browser restarts, it should delete the weights.bin file automatically and stop downloading the Gemini Nano model in the future. This effectively opts you out of Chrome’s on-device AI, even if other AI-related toggles inside the standard settings menus look disabled. If you later decide you want those AI helpers back, you can revisit the same flag, set it to Enabled or Default, and Chrome will once again fetch the model when needed.