Does a VPN Use Data? VPN on Mobile Data Usage Study (2024)

Sadly, you still consume mobile data even when you’re using a VPN.

Using cellular data, and connecting to the internet through a VPN server, still counts towards your cell phone’s monthly data allowance. There’s no way around it.

To understand why VPNs use data, we need to look at how a VPN works.

When you use a mobile VPN app, your phone initially connects to a VPN server, rather than your desired website. The VPN server then connects to the website for you, and returns the information you want.

There are two main advantages to this:

1. The VPN server shields your identity by hiding your IP address, so you can’t be traced.
2. The server can be located in a different country. That means you can access content that is normally only available in that country, such as US Netflix if you’re outside the US.

A VPN also encrypts your data so that your mobile carrier cannot see the content of your activity.

Your mobile carrier can see you’re connecting to a VPN server, but not what you’ve instructed the server to do, or where your traffic from that point onward.

VPN connections still need an existing internet connection to work.

For a VPN to work, you still need a working internet connection. Your traffic still has to travel through your cell phone provider’s network infrastructure in order to reach the VPN server.

Here’s a diagram showing the difference between mobile internet connections with and without a VPN:

While they cannot see the details of the data traveling between your phone and the VPN server, mobile carriers can still measure how much data you are using and charge you accordingly.

In fact, using a VPN will lead to more data usage than not using a VPN, because of the ‘encryption overhead’. We’ll discuss this in the section below.

Alternatively, see if a VPN can give you unlimited data to help you bypass your monthly data limit.

Yes, browsing the internet with a VPN uses more mobile data than not using a VPN.

According to our VPN data usage tests, a VPN increases your data consumption by anywhere between 4% and 20%.

This data consumption increase depends on a number of factors such as which VPN protocol you use. This is known as the VPN or encryption ‘overhead’.

Over time, the overhead can really add up. A two-hour Netflix film streamed in high-definition without a VPN will typically consume about 6GB of data. With a VPN, this could rise as high as 7.2GB.

For users with a mobile data cap, using a VPN will mean you consume your monthly allowance quicker. For travelers, it could mean you pay more for data roaming than you would otherwise.

Here is a brief summary of how the VPN overhead may impact the data usage of different online activities:

EXPERT TIP: To calculate how much data a VPN will use, consider your activity’s data usage without a VPN and then multiply it by 1.04 (for a 4% overhead) or 1.2 (for a 20% overhead).

The reason why a VPN increases cellular data usage comes down to the way information is transmitted across the internet.

When you send and receive data over the internet, it gets divided into ‘packets’. Each packet can only hold a certain amount of data (typically ~1,500 bytes, which is equivalent to ~1,500 plaintext characters).

A packet doesn’t just contain the data you’re downloading or uploading (known as the ‘payload’), though. It also has to save room for information about where the payload has come from, where it’s going, and the internet protocol (IP) version being used.

This information is stored in the IP header, and it requires at least 20 bytes of space in the packet. That means 20 bytes less space for your payload data.

When you use a VPN, the original packet is encrypted and wrapped in a separate packet (with separate headers) in order to route it to the VPN server. As you can imagine, this further reduces the amount of space in the packet for your all-important payload data.

Consequently, a file that would’ve fit nicely into one packet might have to be split up and sent in two packets when a VPN is being used. That is how a VPN causes a 4-20% increase in mobile data usage compared to not using a VPN.

Here’s a illustration of how the payload data is reduced in VPN vs non-VPN packets:

EXAMPLE: An image file that’s 2,960 bytes long fits perfectly into two normal (non-VPN) packets (1480 x 2) with their IP headers (20 x 2). But, when sending the image file over a VPN connection, the additional space taken up by the VPN header pushes the image file into a third packet. This requires an additional VPN header and an additional IP header, increasing the overall data consumption of the file.

There are several techniques you can use to reduce the amount of data your VPN uses:

1Choose the right VPN protocol

VPN protocols are the set of instructions that govern how the VPN client (e.g. your smartphone) communicates with the VPN server.

There are a number of different VPN protocols to choose from, and some are more efficient than others when it comes to data usage.

Which VPN Protocol Uses the Most Data?

We tested five of the most popular protocols to calculate the size of their VPN/encryption overhead. Here’s what we found:

NOTE: We also tested the effect of different key lengths (128-bit, 192-bit, and 256-bit) and different ciphers (AES and Camellia) on data use. The results showed that these factors had very little impact on the protocol’s overhead, despite frequent misleading claims to the contrary.

Roughly speaking, the more data efficient a protocol is, the faster it will be. For instance, WireGuard, IKEv2/IPSec, and PPTP are some of the fastest VPN protocols around.

It is also commonly assumed that more secure protocols will have larger encryption overheads. While this is generally true, WireGuard is currently considered to be secure despite having the smallest overall overhead. Whereas PPTP has known security vulnerabilities but still increases data consumption more than IKEv2/IPSec, a comparatively safer protocol.

2Turn off the VPN

It might seem obvious, but you can stop your VPN using data by simply switching it off.

We would usually recommend that you leave your VPN on all the time, because it’s an invaluable tool for fighting surveillance, protecting your privacy, and keeping you safe.

However, if you’re just using your VPN to occasionally unblock foreign Netflix libraries or protect your identity when torrenting, and data usage is an issue, it might make sense to turn it off when you aren’t engaged in those activities.

By only using the service when strictly necessary, you can avoid the VPN overhead and make your monthly data allowance last longer or avoid paying more in data roaming charges.

3Use Split Tunneling

In fact, some VPN services offer a specialized feature to help you do just that. VPN split tunneling lets you specify which apps and services you want to run through the VPN connection and which you don’t.

For example, you might choose to protect your sensitive web browsing and email activity with the VPN, but transmit high-bandwidth activity like streaming and gaming outside of the VPN in order to avoid the overhead.

Not every VPN offers split tunneling, though. We recommend using ExpressVPN or NordVPN if it’s something that appeals to you.

4Enable compression

Compression is a method used by many VPNs to minimize the amount of data usage. It’s a bit like zipping a file before it goes over the internet and is especially effective for image file transfers.

Typically, your VPN will have compression enabled by default if it uses it. But it’s always worth taking a look in the Settings menu to double-check.

Its effectiveness depends on whether the images and other content were compressed in the first place.

Most internet-friendly file formats are compressed already, and uncompressed text is only a small part of the data we typically download.

That said, if extra compression is available, use it.

Cell phone plans often include a limit on the amount of data you can use per month. Using a VPN will not let you overcome this limit or give you access to unlimited data.

In fact, a VPN consumes more data than not using one, so you’ll actually reach the data cap sooner.

You may have seen VPN companies advertising ‘unlimited bandwidth’ or ‘no data cap’. This refers exclusively to the VPN service itself – it does not relate to your cell phone’s data limit. Your activity on a VPN without a data cap is still subject to your mobile provider’s data cap.

While premium VPNs tend to offer unlimited bandwidth, most free VPNs will impose their own data caps. On top of your mobile’s monthly data allowance, you’ll need to be aware of how much data you’re passing through the VPN each month with these services. For a free VPN with unlimited data, check out Proton VPN Free.

Cellular providers sometimes apply a ‘soft’ cap, which works by slowing down your traffic once you’ve used up your allotted amount of data. The idea is to ensure the network is being used fairly and to stop heavy users consuming all the bandwidth.

Often, providers target these ‘soft’ caps at specific high-bandwidth activities, such as video streaming, torrenting, or gaming. As an example: your plan might let you enjoy unrestricted bandwidth for the first 10GB of mobile data each month. Then, after you reach this limit, your streaming speeds become throttled to a maximum of 20Mbps.

Using a VPN can stop throttling in this scenario. By encrypting your traffic, the mobile carrier could no longer see what your activity was and so couldn’t recognize that you were streaming. You’d therefore be able to enjoy unlimited streaming speeds beyond the 10GB limit.

NOTE: If the ‘soft’ cap applies to all traffic, and not just to specific activities, then a VPN will not be of any use. Your provider will just throttle all of your speeds, without needing to know what you’re doing.

Another easy mistake to make is thinking that a VPN will help to avoid data roaming charges when abroad. If you connect to a VPN server in your home country, can’t you trick your mobile carrier into thinking you’re still at home and so still eligible to use your domestic data plan?

Unfortunately not. Mobile usage is charged based on the location of the cell tower you connect to, which will be closest to wherever you (and your phone) are. Even with a VPN, roaming charges apply.

Here’s a summary of some different circ*mstances and how a VPN might help or hinder you in each:

EXPERT TIP: Some mobile providers offer special plans where they cap data at a specific amount, but let users have unlimited data for social media use. If you’re on a plan like this, make sure you’re not running your social media activity through your VPN. Your mobile provider won’t be able to tell you’re using social media and your activity could end up counting toward your general data allowance, if you do.

A VPN uses data. In fact, a VPN will use up more cellular data than not using a VPN because of the encryption overhead.

This means a VPN won’t let you:

• Bypass a monthly data cap.
• Access unlimited mobile data.
• Avoid data roaming charges while abroad.

You may be able to overcome certain ‘soft’ data caps, though – where network providers throttle bandwidth-heavy activities are throttled after you’ve consumed a certain amount of data.