Tech Talk

Here’s How to Find Out What Google Knows About You

Or at least, what it thinks it knows about you

Rionaldi Chandraseta
Apr 16 · 7 min read
Photo by Paweł Czerwiński on Unsplash

In Q3 2020, Google generated $5 billion through its advertising service, Google Ads. This number comes from advertisers that pay Google to put their ads for display, but what makes Google ads so widely used?

Google uses AI-powered targeted marketing, which means they will only show the advertisement to relevant people. Relevant people are the intended target market, for example parents of a newborn will be more likely to click on an ad about baby stroller compared to average individuals.

So, how does Google get this kind of information about a person?

It’s pretty easy actually if you think about it. Over 1 billion people use Gmail. If you have booked a flight or a hotel and Google adds them automatically to your Google Calendar, you know they are automatically going through your emails and their attachments.

In March 2021, 64.2% of Internet users use Google Chrome. YouTube also claims it has 2+ billion active users monthly. Last but not least, 71.8% of phone OS is Android, which is created by Google. These Google products will keep track of your usage and collect data about you.

Then what does Google know about us?

For years, we don’t get to know what makes ourselves get targeted by certain ads, let alone control what ads to see. However, a couple of months ago Google finally give us access to do just that.

Go to

Screenshot of by Author

You can simply click the switch to turn the Ad Personalisation off. I also tried to do this and you can skip to the end of this article if you want to know what happens.

Dissecting What Google Knows

If you click on the Advanced tab, you would see what Google has figured out about yourself. Here’s a screenshot of mine.

Screenshot of Google’s Personalised Ads by Author

The list goes on and on, and this is where I counted 197 items that Google will show me ads for.

If you click on some of the listed traits, you can see the detailed description of each and sometimes a brief explanation why Google detects those items.

Google can easily infer traits such as Age Group and Gender from the information you put when registering for your Gmail account. However, other more obscure items such as relationship status and education status should have been much harder to get.

Most of them seem quite accurate, which is scary to be honest.

What Google Got Right

Marital status, parental status, job industry, company size, education status, all of them are correct somehow.

Both me and my girlfriend are not active on any social media, so it is a surprise to us when Google figured our relationship correctly. They might get information about job and education related stuff from LinkedIn for all we know.

The list also includes an assortment of TV genres such as “TV Documentary & Non-fiction” and “TV Sci-Fi & Fantasy Shows” which I highly suspect gathered from Netflix watch history.

I came across “Extreme Sports” and “Ferrari” on the list, even though I don’t know how I got associated with Extreme Sports or Ferrari, since I never specifically searched for them.

After a bit of scrolling, I also found Mercedes-Benz on that list and that’s where it clicked. I was watching Formula 1 highlights on YouTube, which is classified as extreme sports and has both the Ferrari and Mercedes-Benz team taking part in it.

What Google Got Wrong

Google got some things wrong, though, they tagged me “Pets” and “Pet Food & Pet Care Supplies”. I enjoyed looking at dog videos in Instagram, but I definitely don’t own one currently.

Some items that I could not understand are Greetings Cards, Maritime Transport, and Performing Arts. I went through my search history in Google and YouTube but I couldn’t link anything to these items.

Finally, it seems like Google needs to improve the detection for music preference. Google tagged a lot of music type from classical to jazz to metal. They got some of them right, but I am definitely not a fan of metal and alternative music.

That said, out of 184 items that Google thinks I will be interested in, only around 10% of them were wrong. This means Google’s ads personalisation system reached 90% accuracy on determining my interests.

Turning Them Off

Screenshot of Turning Off Interest by Author

You can simply turn them off by clicking on an item and then select Turn Off.

I tried turning off “Investing” to see if I will still get advertisements from those online brokers.

After about an hour of visiting random YouTube videos to get ads, I can safely say I did not encounter any ads related to investing.

When I turn them back on, though, I immediately get ads about online broker on my second video.

Screenshot of Turning Off Advertiser by Author

Some listed items are actually the name of advertisers instead of an area of interest. Mine includes some banks, PlayStation and M1 (telecommunication service provider in Singapore), probably because I use their services.

Trying to turn them off will open another pop-up window that says “Advertisers you turn off will stay off for at least 90 days.” Which means Google might turn them back on automatically after 90 days if they want to.

I tried turning some of them off, but could not really feel the difference since I rarely get any ads from these advertisers, anyway.

Turning All of Them Off

Screenshot of Turning Off Ads Personalisation by Author

Out of curiosity, I tried turning off all the ads personalisation to see what advertisements that Google will give.

To test it, I need to find a website with Google Ads, and what better website than Google’s own YouTube that is infamous for the double ads in the start of almost all videos.

To my disappointment, I still got the same stock broker advertisements I usually get. So I tried another video. This time around, it was also the usual get-rich-quick gurus in Singapore.

I logged out of YouTube and log back in again. I started getting more advertisements in Chinese, which is a commonly spoken language in Singapore. I still got the usual entrepreneurship guru ads, but I think it’s because they paid to get shown to the whole of Singapore.

I asked my friends who live in Indonesia and Japan to see if they get different ads after turning ads personalisation off, and yes they receive local ads instead of the usual ones. This confirms that Google will instead rely on other data such as geolocation for choosing the ads.

Props to Google for actually turning the personalisation off when requested.


Going through my ad personalisation page actually gives me some insights about myself. There are a lot of moments where I say “This is wrong, I don’t like these things,” followed by “Well, come to think of it, I did search for this thing.”

It also motivates me to live healthier. Seeing both “Fast Food” and “Soft Drinks” on the list makes me think I have ordered them one too many times.

Does turning ads personalisation off prevent Google from collecting your data?

I believe Google will still track your search history, YouTube videos history, and other information to build an online persona of yourself even with the settings turned off. Disabling the ads personalisation will stop Google from using these data to pick the perfect ads for you, but it doesn’t mean they will stop collecting data about you.

One last experiment I tried is searching about baby products to see if Google would change my Parental Status to true or something, but it hasn’t worked so far. My guess is that it has to occur repeatedly instead of a one-off, just in case you are looking for gifts for your niece or nephews instead of for your own children.

What interesting traits did Google catch about you?

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