I opened Activity Monitor on my MacBook last Tuesday and noticed Chrome was using 8 GB of disk space for something I had not downloaded on purpose. The file was sitting in my user library, unnamed in any UI I had ever seen, and it was 4.7 GB. It was not a cache, not a profile backup, and not a video. It was an AI model Chrome had pulled down to power features I had never turned on. If you use Chrome and you have not checked this folder in a while, you should look.
What the file is
The file is called weights.bin. It lives inside Chrome’s user data directory, under a folder named OptGuideOnDeviceModel, and it is the on-device version of Gemini Nano, Google’s small AI model that powers Chrome’s built-in AI features. Chrome can use it for writing assistance, scam warnings, tab organization, page summaries, autofill suggestions, and a handful of other tools you may or may not have explicitly enabled. The model runs locally on your computer, which means Chrome has to download the model file to your computer first.
This is not a hidden feature. It is documented in Google’s Chrome Help pages and developer documentation. It is also not a small download. The current model size is in the 2-5 GB range, depending on which version Chrome has pulled down, and Chrome will update the model in the background as new versions release. If you have not paid attention to it, the model is probably already on your machine.
Why Chrome downloads it
The pitch from Google is that on-device AI is faster and more private than cloud-based AI for the kinds of features Chrome wants to add. Tab organization does not need a round trip to a server. Scam warnings should not depend on a network call. Writing assistance should keep working on a flight with no Wi-Fi. The on-device model makes those features work offline and keeps the input data on your machine.
The trade-off is the disk space. A 2-5 GB file is not enormous by modern standards, but it is also not small. If you have a 128 GB MacBook Air, a 5 GB AI model you never asked for is a meaningful chunk of your drive. If you have a 512 GB MacBook Pro with a 1 TB external SSD, you will probably never notice. The user experience depends entirely on your hardware.
There is also a battery cost. Running an AI model locally uses CPU and, on machines with a neural engine, the NPU (neural processing unit, a dedicated chip designed to run AI workloads faster than the main CPU). The battery hit is small for occasional use, but if you have several AI features turned on at once and you are on battery, you will see the drain.
How to check if it is on your machine
Open this URL in Chrome:
chrome://on-device-internals
You will see the model status, the version, the current size on disk, and a button to delete the model. If you want to verify the file path manually, the location depends on your operating system.
On Windows, the file is at:
C:\Users\<you>\AppData\Local\Google\Chrome\User Data\OptGuideOnDeviceModel\<profile>\weights.bin
On macOS, the file is at:
~/Library/Application Support/Google/Chrome/OptGuideOnDeviceModel/<profile>/weights.bin
On Linux, the file is at:
~/.config/google-chrome/OptGuideOnDeviceModel/<profile>/weights.bin
The <profile> part is the name Chrome uses for your default profile, which is usually Default for the first profile and Profile 1, Profile 2, etc. for additional profiles. If you have multiple Chrome profiles, you may have multiple copies of the model, one per profile.
How to remove it
If you want the disk space back, you have two options. The first is to open chrome://on-device-internals and click the delete button. Chrome will remove the model file. The next time you use a feature that needs it, Chrome will re-download the model in the background. This is the cleanest option if you want to use the features but reclaim the space temporarily.
The second is to disable Chrome’s on-device AI features entirely. Open Chrome’s settings, search for “AI” or “experimental features,” and toggle off the features you do not want. With the features off, Chrome should not re-download the model. The exact setting names change as Google ships updates, so if you cannot find the toggle, the URL above is the more reliable way to manage the file.
If you delete the model and Chrome re-downloads it within a few days, the AI features are probably still enabled somewhere. Check the experimental features list carefully. Chrome will not redownload the model on its own if the features are off.
What I would tell past me
If I could send a message back to the version of me that first noticed the 8 GB Chrome footprint, I would say three things.
- On-device AI is going to be a real category, and the disk cost is going to surprise people. The first generation of these models is 2-5 GB. The next generation is going to be larger. Budget for it like you would budget for any other system requirement.
- The
chrome://on-device-internalspage is the cleanest way to manage the model. The settings UI changes with every Chrome update. The internals page is stable. - If you do not use the AI features, the model is wasted space. A 5 GB file is not free. The features are useful, but only if you actually use them. If you do not, delete the model and turn the features off.
The bigger lesson is that browsers are now shipping with significant on-device AI capabilities, and the storage and battery costs are part of the deal. Chrome is the first major browser to do this at scale. Safari and Firefox are working on similar features. If you are paying attention to your disk space and your battery life, the browser’s AI model is the new thing to monitor.
Trade-offs
Chrome’s on-device AI is not free, in any of the dimensions that matter. The model file is 2-5 GB on disk. The model uses CPU and NPU cycles when the features are active. The model downloads itself in the background without asking first. The features themselves are useful for some users and ignored by others.
In our case, the features earn their keep for the writing assistance and the tab organization, but not for the scam warnings, which fire rarely and are easier to verify by hand. The math will be different if you use Chrome’s AI features heavily, or not at all. There is no universal answer.
The model also raises a question about long-term disk hygiene. A 5 GB file that updates itself in the background is a new category of “what is using my disk space” that older disk-cleanup tools do not know about. If you use a tool like DaisyDisk or CleanMyMac, the model file will show up as “Chrome” and you will not be able to tell from the UI that it is the AI model specifically.
The features that justify the cost for most users are:
- Writing assistance. Tone and length suggestions in text fields, useful enough to keep on.
- Tab organization. Groups similar tabs into a labeled cluster, helpful for research sessions.
- Page summaries. Bullet-point TLDR for long articles, mixed quality but occasionally useful.
- Scam warnings. Flags suspicious pages during form fills, fires rarely and is hard to evaluate.
If you use most of these, the model is worth the disk space. If you use none of them, deleting the model and turning the features off is the cleanest path. The middle ground is to keep the model and accept the disk cost as part of using a modern browser. There is no version of Chrome that ships the AI features on demand without the model file.