How much data does a VPN really use?

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They're super useful, but how high is their data consumption?

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From a technology standpoint, there's nothing quite like going online and knowing everything you do is protected, safe, and secure. That’s the real value of the best VPN (Virtual Private Network), which creates a secure tunnel for all of your Internet activity.

For anyone who uses a VPN and trusts the connection is providing an extra layer of privacy and anonymity, there may still be a question mark lingering in the air – does a VPN increase the amount of data you use? 

This is particularly important if you're connecting on a network where your speed and access is throttled, or if you have a data plan that monitors and tracks your usage and charges you accordingly, so mobile users take note.

A VPN doesn't make you immune to charges from you ISP for using more than your allotted data. While the Internet Service Provider (ISP) can’t see what you are doing online or track your identity, they still see the bandwidth usage.

And, while you might think a VPN doesn’t add much data usage beyond what you’d expect, there is some overhead – more than you might think if you're downloading movies, playing games, or archiving files. It does tend to add up for every web visit, every download, and every movie you stream over a period of days, weeks, and months.

How VPNs work

A VPN (like, say, ExpressVPN) creates a tunnel between your device and a web server, and this provides the protection you're after. It insulates you from prying eyes that might want to know which sites you're visiting and then show you relevant ads. We’ve all been there. You start searching for a new laptop and then you see HP and Lenovo ads on social media. How did they know? It’s because your connection isn't protected – all of those website searches are free to track.

When you create a VPN connection, everything you do is secured using encryption. For anyone who has ever created a zip file, you know how it works (at least from a more simplistic level). Encryption makes every file untraceable and unbreakable, such that advertisers and even government agencies can’t see what you are transmitting.

Backing up even further, it should be noted that the internet is essentially a way for a web server to distribute files. When you visit BuzzFeed, Tom's Guide, or The Washington Post, you're connecting to a server and then transmitting files back to your client – usually a series of HTML files, images, videos, and other content. You're transferring the content from a remote location to your device (and back). A cookie installed by the web server can track every page you visit.

How much data does a VPN use?

A VPN encrypts those files during the transfer, and that process does create some overhead. By most estimates, the encryption process adds about 10-15% more data usage.

Computing this is fairly easy. Let’s say you're downloading a large HD movie file that’s 2GB of data. Over a normal public connection, the data usage would be exactly 2GB. However, over a VPN that encrypts the data for you, the data usage increases. Since 2GB is actually 2,048 MB of data, it means you're technically transferring more like 2,348 MB in total.

Now, this multiplies for every single file you access. Even in one single day, if you stream several HD or 4K movies over a VPN, you might be adding as much as 1 or 2 GB of extra data just from the encryption that occurs. If you add up the total over days or weeks, your VPN could even be generating several hundred GBs worth of encryption data.

That's why for most people, getting a free VPN won't be the ideal solution. They largely limit the amount of data you can use per day or per month.

What to do about extra data usage 

There's a decision to be made here. For anyone who uses an internet connection that is monitored for high data usage such as satellite Internet or a cellular data connection you use in your home (using a hotspot device from a company like HTC or Netgear), a VPN won’t prevent you from going over your allotted amount and will actually add more overhead (about 10-15%). That means you will use up more data faster and in a shorter period of time.

In most cases, the answer is in limiting how much data you transfer per month if you know you need to use a VPN but also have limited data. That can be difficult, especially if you're using a VPN for work-related tasks or because you are dealing with sensitive and protected files. However, there is another option available for VPN users.

One is to decide when you really need to use a VPN.

For example, if you are mostly concerned about advertisers tracking what you do online, you can leave the VPN running on your computer or phone during all of that data usage activity. The extra usage on your Internet plan might be minimal if all you are doing is visiting sites and researching products or checking on the news of the day.

That might not be why most people use a VPN – it’s more common to want to access blocked streaming content and torrenting sites. If you know you need to use a VPN, it is helpful to calculate the amount of data transfers you do per day that might impact your Internet usage. It might even make sense to track the usage – say you download two or three files in a week. You can add the 10-15% extra transfer amount and keep tabs on your total for the week.

For some users, you may be able to turn the VPN off for certain types of activity. For example, if you are accessing the Pluto TV app to watch television shows and you are in the United States, the app is free to use – you don’t need a VPN per se. You can enable the VPN when you are visiting websites and then turn it off when you want to watch reruns of The Office.

Also, the best services provide a feature called Split Tunneling. In essence, the VPN only encrypts what you tell it to, and it does so automatically. So, you could tell it to always encrypt BitTorrent traffic, but ignore Chrome traffic so it won't encrypt the data you're using to watch YouTube.

That’s the main benefit of a VPN - you have a choice of when to use it, when to disable it, and when to do a combination of both for all your Internet travels.

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John Brandon