How to Reclaim 4GB of Storage Space from Chrome's Hidden AI Model

Introduction

Is your Mac's storage mysteriously disappearing? If you use Google Chrome, you might be the unwitting host of a 4GB file called weights.bin. This file is part of Google's Gemini Nano AI model, which powers on-device features like scam detection, autofill suggestions, and the 'Help Me Write' tool. The problem? Chrome downloads this hefty file without asking for your permission, eating up precious drive space. In this guide, we'll show you how to detect, remove, and permanently prevent this hidden AI model from hogging your storage.

How to Reclaim 4GB of Storage Space from Chrome's Hidden AI Model — Source: www.macrumors.com

What You Need

A Mac with Google Chrome installed (version 148.0.7778.97 or later)
Administrator access to your Mac
Finder (for manual file checks and deletion)
About 10 minutes of your time

Step-by-Step Instructions

Step 1: Confirm the AI Model Exists on Your Mac

First, verify that the mystery file is actually present on your machine. Follow these steps:

Open Finder and click Go in the menu bar at the top of the screen.
Hold down the Option (Alt) key – you'll see a new option: Library. Click it.
Navigate to Application Support ➝ Google ➝ Chrome ➝ Default.
Look for a folder named OptGuideOnDeviceModel.
If the folder exists, open it and check for a file called weights.bin. Right-click it and choose Get Info to see its size – it should be around 4GB.

If you don't see the folder or file, congratulations – your Mac hasn't been affected. Skip to the Tips section for future prevention ideas.

Step 2: Temporarily Delete the File

Simply trashing weights.bin isn't permanent – Chrome will likely re-download it the next time you launch the browser. But we'll do it anyway as part of the cleanup. Here's how:

From the same Finder location (~/Library/Application Support/Google/Chrome/Default/OptGuideOnDeviceModel), select the weights.bin file.
Drag it to the Trash or right-click and choose Move to Trash.
Empty the Trash to reclaim the space immediately.

Step 3: Disable Chrome's On-Device AI Feature (Permanent Fix)

To stop Chrome from re-downloading the model, you must turn off the on-device AI setting. This is the only reliable way to regain control:

Open Chrome and click the three‑dot menu (⋮) in the top‑right corner.
Select Settings from the dropdown menu.
In the left sidebar, click System.
Find the toggle labeled On-device AI and switch it off.

Once disabled, Chrome will remove the model (if it hasn't already) and stop downloading it with future updates. Note that this also disables any AI‑powered features that rely on the model – a trade‑off worth making for extra storage.

Step 4: Use Chrome Flags If the Toggle Is Missing

Some users report that the On-device AI toggle doesn't appear in their Settings. If that happens, use Chrome's experimental flags to force disable AI features:

Type chrome://flags into Chrome's address bar and press Return.
In the search box at the top, type AI to filter relevant flags.
Look for flags like Enable AI features, Gemini Nano, or anything mentioning “on‑device AI.”
Set each such flag to Disabled using the dropdown menu.
Click the blue Relaunch button that appears at the bottom to restart Chrome.

After relaunch, go back to Finder and delete the weights.bin file again if it's still there (it may have been removed automatically). This method ensures Chrome won't quietly re-enable the feature.

Step 5: Verify the Removal

To make sure the space is truly reclaimed and the file won't return:

Restart Chrome completely (quit the app, then launch it again).
Revisit the folder path from Step 1 – the OptGuideOnDeviceModel folder should be gone, or at least contain no weights.bin file.
Check your Mac's storage in About This Mac ➝ Storage – you should see the 4GB freed up.
Optionally, repeat the steps after a few days to confirm Chrome hasn't re‑downloaded the model.

Tips & Considerations

Know the trade‑offs: Disabling on‑device AI means you'll lose features like scam detection, autofill suggestions, and the “Help Me Write” tool. If you rarely use those, the extra 4GB is a worthy trade.
Alternative browsers: If you're concerned about such silent data‑hogs and want a more transparent experience, consider switching to Firefox, Brave, or Safari – none currently install large AI models without consent.
Keep an eye on updates: Google may change how Chrome handles on‑device AI in future versions. Periodically check the System settings to ensure the toggle hasn't been re‑enabled.
For technical users: You can also use Terminal to locate and delete the file, but the Finder method is simpler for most people.
Backup first: If you're unsure about any step, create a Time Machine backup before proceeding – just in case.

By following these steps, you've reclaimed a full 4GB of storage and restored your privacy from Chrome's unwanted download. Remember: you're in control of your machine, not the other way around.