Here's the one piece of personal info that you shouldn't share online

Attractive young people at a birthday party blowing out candles on a cake.
(Image credit: Monkey Business Images/Shutterstock)

There's a key piece of information about yourself that you may be eager to share online, but that you really shouldn't let other people know. It's your birthday.

This may not make sense at first. Everyone loves getting birthday presents. Most people like receiving birthday wishes on Facebook, which tells everyone your birthday by default.

But telling the world your birthday puts you at greater risk of identity theft. That's because your date of birth — the exact day, month and year you came into this world — is a keystone of your identity. It's almost as important as your name.

Most people aren't aware of this. In the past few weeks, hundreds of Americans have celebrated getting their COVID-19 shots by putting photos of their official vaccination cards on Instagram, Facebook or Twitter.

That's a terrible idea. Right under your name on the vaccination card is the your date of birth, and many people are not covering up their birthdays. These people don't know it, but by putting their names and their dates of birth together online, they're putting themselves at risk.

Your birthday is a key data point

To successfully steal your identity in the United States, a thief, in most instances, would need to put together four personal data points: your full name, your current address, your date of birth and your Social Security number. 

Your name, even your full name, and your street address are not too hard to find online. Your Social Security number should be very hard to find. 

It's the third item, your date of birth, that you want to make as hard to find as you can. That won't make theft of your identity impossible, but it will make it more difficult.

Another reason: Your date of birth is often used to verify your identity. Some banks want people to enter their birth dates when they're logging into their online accounts. Other services will use your date of birth as the answer to a "security question" when you want to change your password. You can see how crooks and thieves could abuse your date of birth if they knew it.

Likewise, if you have a common name, there's a certain amount of protection in obscurity. For example, there must be thousands of people in North America named Michael Anderson, and it would be hard to narrow down a search for "Michael Anderson" to one person with only a name. But if you knew that your Michael Anderson was born on Feb. 28, 1985, it would be a lot easier.

Notice that we're using the term "date of birth," which includes your year of birth. Telling people your "birthday" usually just means the day and month, which is what Facebook, for example, likes to make public.

So is making your birthday public, without the year, okay? Not at all. 

Obscuring the year of birth doesn't offer much protection. All an identity thief has to do is check out your class-reunion photos on Facebook. If they can figure our your age within a year or two, they can guess your year of birth.  

How to limit who can see your birthday

Unfortunately, you're supposed to give Facebook your birthday when you sign up for the service. 

Many other online services want it too. You don't necessarily have to give them your actual birthday, although that could lead to complications later on. But in most cases, you can limit who sees it. 

LinkedIn, Snapchat and Twitter don't require your birthday, so don't provide it if you haven't already. 

Instagram doesn't require it either, but it will copy your birthday from your Facebook account if you have one. Fortunately, Instagram doesn't make it public.

Apple and Microsoft do require your birthday to set up accounts, but neither make it public. 

How to hide your birthday in Facebook

In a desktop browser, log into Facebook, then click your profile photo in the upper left. From there, click About > Contact and Basic Info. Scroll down to Basic Info and click the pencil icon to the right of your birthday. Change both the birthday and the year of birth to "Only me."

In the Facebook app, tap the "hamburger" menu in the top right, then scroll down and tap "Settings & Privacy" and tap "Settings." Scroll down to the "Audience Visibility" section and tap "Profile Information." Scroll down to "Basic Info" and tap Edit. Change your birtday and birth year to "Only Me."

Facebook changes its interface and settings menu constantly, so if the above steps don't work, check Facebook's own help page on the topic here .

How to hide your birthday in Google

In a desktop browser, open Gmail or another Google service and log in. Click your profile image in the upper right and select "Manage your Google Account." Click "Personal Info" in the left-hand menu. Select "Birthday" and under "Choose who can see your birthday," choose "Only you." 

The procedure is the same on a mobile device, except that you have to start by tapping the Google app icon.

How to hide your birthday in LinkedIn

In a desktop browser, log into LinkedIn and click your profile photo. Click Contact Info, then click the pencil icon in the windows that pops up. Scroll down to Birthday. 

You can roll back the month and day fields to just "Month" and "Day," removing your birthday from your LinkedIn account. If you'd rather leave them, then select "Birthday visible to" under those fields to "Only you."

How to hide your birthday in Snapchat

In the Snapchat mobile app, tap your profile photo. Then tap the settings icon — it looks like a gear — in the top right. Scroll down to My Account and look for "Birthday." 

If it's blank, leave it alone. If your birthday is in there, tap it and then make sure the "Birthday Party" option is unchecked. Otherwise, all your Snapchat friend will be told when it's your birthday.

How to hide your birthday in Twitter

In a desktop browser, select your profile photo and then select "Edit profile." Scroll down to "Birth date" and select "Edit." Change both "Month and day" and "Year" to "Only you." 

Paul Wagenseil

Paul Wagenseil is a senior editor at Tom's Guide focused on security and privacy. He has also been a dishwasher, fry cook, long-haul driver, code monkey and video editor. He's been rooting around in the information-security space for more than 15 years at, SecurityNewsDaily, TechNewsDaily and Tom's Guide, has presented talks at the ShmooCon, DerbyCon and BSides Las Vegas hacker conferences, shown up in random TV news spots and even moderated a panel discussion at the CEDIA home-technology conference. You can follow his rants on Twitter at @snd_wagenseil.