If four letters could sum up the modern world, “data” would be pretty close to the mark.

We’re constantly told that this is the age of Big Data and that our “data selves” are as important as our bodies and minds. And we’re also advised to keep our data closely protected, with good reason. Data breaches can ruin our finances and lead to identity theft, so it’s advice worth taking.

Virtual Private Networks (VPNs) are top of the list when it comes to data security. But how do these apps use data? Are they data hogs for mobile devices, and will they have an impact on your data bills?

This blog will explain all you need to know about VPN data usage. Hopefully, we can dispel some myths and set matters straight, helping you find the ideal VPN for your security needs.

Does a VPN use data?

VPNs are intended to encrypt the data you send and to anonymize your online identity. These features lead some people to argue that VPNs can hide the amount of data you use from ISPs or mobile providers.

This could potentially open the way to lower bills while working around the data capping policies used by many ISPs as part of their tiered payment structures.

But is it true? Well, one thing needs to be understood straight away: the answer to the question of “does VPN use data” is: yes. Encrypted traffic from VPNs must pass through your ISP’s servers before it can be processed by VPN servers. That’s just an unavoidable aspect of the web’s architecture.

When your data flows through your ISP or mobile company’s servers, it won’t be possible to find out what it contains. You can rely on your VPN to encrypt information. But VPN data usage is much harder to conceal.

Your ISP will be able to monitor the raw amount of data you are sending and receiving. So in theory, your bills shouldn’t be reduced or increased by VPN usage. But that’s not exactly the whole story.

Does a VPN increase data usage?

For one thing, VPNs can actually increase the amount of data you consume, leading to higher monthly bills.

Why is this? Well, the answer lies in the way VPNs encrypt your data. Encryption always comes with a price. When data is encrypted, it almost always becomes “larger” than the original, occupying more bandwidth.

The size of this “price” depends on the efficiency of the encryption being used, but it can work out as much as 15% of your overall bandwidth. That’s a large chunk of data – especially for torrenters or streaming fans.

Which VPN protocol uses the least data?

All VPNs use protocols to wrap data in “tunnels” which ensure it is secure as it weaves its way around the web. But not all protocols are equal, and some use far less data than others.

For example, the older Point to Point Tunneling Protocol (PPTP) remains one of the fastest available. However, it might not be very secure. In fact, if you are transmitting confidential payment information, you should never use PPTP. But if you are streaming from Netflix, it’s a good option thanks to the low encryption overhead.

L2TP/IPsec is more advanced from a security standpoint, and almost impossible to break. It’s also relatively efficient, sapping very little data from your connection. However, it’s not that tough to intercept, and as a result, often struggles to work around geo-blockers.

Microsoft’s SSTP is another option (as long as you are running Windows, so smartphone users are out of luck). It’s not the most secure but works around blockers reliably.

However, SSTP pales in comparison to OpenVPN. Able to work on all platforms, OpenVPN is efficient (though not as quick as L2TP/IPSec or PPTP) and flexible. It’s also very secure, so it strikes a balance between speed and security. Users should also note that OpenVPN comes in a few forms. For example, there are 256-bit and 128-bit versions, and “Stealth” varieties as well. 256-bit Stealth OpenVPN is comfortably the slowest – reflecting the trade-off between encryption and speed.

Finally, there’s IKEv2. Designed for mobile devices, IKEv2 is the best option for Android and iOS. It’s fast, data efficient, and secure. You won’t find it bundled with all VPNs though, but hunt it down if you can.

Does using a VPN count against data caps?

Now, let’s move onto one of the key questions about VPN data usage. The issue here isn’t whether a VPN does or does not use data. That’s non-negotiable. Instead, we need to know whether VPNs can evade data capping imposed by mobile companies and ISPs. If so, that could save users huge amounts from their telecoms bills.

As we explained above, generally speaking, ISPs will be able to tell how much data you consume. So on the face of things, it shouldn’t be possible for VPNs to fool ISPs into thinking you are consuming less than you actually are.

However, things aren’t quite so simple. Some caps are more complex, stipulating separate caps for web browsing, streaming, P2P downloads, etc.

If this kind of “soft” capping is in place, VPNs can be a big help. While they can’t hide raw data usage, they can make it hard for ISPs to tell the kind of data you are consuming. So, if your provider operates a cap on streaming video, a VPN will make that cap tough to enforce.

So, if you’re wondering: “can I use a VPN to get around my ISP’s data cap,” you may be out of luck. VPNs are impressive security tools, but they aren’t miracle workers, and you need to be realistic about what they can achieve.

What can VPNs do to combat ISP capping?

However, there is one problem that VPNs can almost certainly help with: ISP throttling.

Many internet providers have started to throttle connections when they see users accessing certain sites. For example, your ISP has the ability to tell when you are downloading data packets from streaming platforms like Netflix or HBO.

They aren’t supposed to throttle connections to suit their wider needs, but ISPs often do. Instead of allowing users to freely stream video, they impose speed restrictions to free up bandwidth for others.

This can be really irritating if you’ve paid for a subscription to Netflix, but Verizon decides to impose a speed-block. Fortunately, VPNs usually neutralize this kind of throttling.

As we noted above, VPNs make data packets tough to inspect, so Netflix data just gets lost in the flow – a handy tool for TV and movie fans who always want silky smooth visuals.

Are there factors which affect how much data your VPN uses?

We’ve talked a bit about why VPNs use data, and how encryption can show up on your monthly bills. But is there anything else that can impact how much data your VPN consumes?

Possibly. If your VPN maintains very slow servers that are geographically distant from your physical location, this can make them less efficient. Problems with authenticating data can cause repeat requests as well, which shows up as extra data use.

In some cases, lower quality VPNs also send ads to your browser or client, which adds more baggage to your bandwidth. And, in the worst cases, they can inject malware or tracking cookies. This can also add an extra burden to your connection.

But in the best VPNs, the only real overhead derives from encryption and protocols. And the very best keep those overheads as slight as possible.

Choose a VPN which uses data as efficiently as possible

So, what have we learned? For starters, VPNs don’t have a magic wand. They can’t stop ISPs or mobile companies seeing how much data flows between your device and other web servers. So the basic amount of data you consume can’t be concealed.

Moreover, VPNs inevitably add an “encryption overhead” on top of the data you use. That’s a very good thing from a security perspective, as it shows that your data is being properly protected.

But VPNs can help to work around forms of ISP throttling, and they are especially useful in accessing streaming platforms. Their strength lies in the way they can hide the nature of your data, not how much data you use.

When choosing a VPN, you need to take a few things into account. Firstly, fast servers will compensate for the encryption overhead. And they need to be balanced by advanced protocols like OpenVPN, with 256-bit encryption.

If you strike a balance between speed and security, you won’t blitz your data caps, and you won’t expose your data. And remember: not all VPNs manage to satisfy both requirements, so choose wisely and don’t be fooled by promises of defeating data caps or ultrafast speeds.