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Does a VPN Use Data? A Beginner’s Guide to Using VPNs on Mobile Data

JP Jones - CTO @ Top10VPN

JP is our CTO. He has over 25 years of software engineering and networking experience, and oversees all technical aspects of our VPN testing process. Read full bio

Our Verdict

Yes, a VPN uses data. In fact, our recent study found that using a VPN on your cell phone increases mobile data usage by 4-20% (depending on which VPN protocol you use). This means you can't use a VPN to overcome monthly data caps or get unlimited roaming data. However, you can bypass certain forms of 'soft' cap and bandwidth throttling.

illustration of a VPN protecting the mobile data usage on a smartphone

A virtual private network (VPN) encrypts your data to create a private and secure internet connection. It prevents cell phone carriers, such as Verizon Wireless, from tracking your online activity and lets you access websites and services that aren’t normally available in your location.

Mobile VPN apps are widely available on both Android and iOS devices. They’ll protect your traffic when you’re connected to WiFi and when you’re using your phone’s cellular data (e.g. 4G).

One question that appears a lot, though, is how does using a VPN on your phone affect data usage?

We see a lot of confusion around this topic, as well as a great deal of false information. In this guide, we’ll set the record straight.

Short on time? Here are some quick answers to the most common questions we’ve seen:

Does a VPN work on cellular data?
Yes, a VPN works on cellular data in very much the same way it works on WiFi. Simply turn on your VPN while connected to 3G or 4G and it’ll encrypt your web traffic and hide your IP address. Read more.

Does a VPN use data?
Yes, you will still consume data when you’re using a VPN. The VPN encrypts and protects your online activity, but it doesn’t stop your cell phone provider from being able to measure how much data you’re using. Read more.

Does using a VPN use more data?
Yes, using a VPN actually increases your data usage, compared to not using a VPN. This is because of the ‘VPN overhead’. Read more.

How much extra data does a VPN use?
Our recent investigation found that a VPN increases data use by a minimum of 4%, but it can rise as high as 20% if you’re using the OpenVPN TCP protocol. Read more.

Does using a VPN give you unlimited mobile data?
No, a VPN won’t give you access to unlimited cellular data because it doesn’t let you bypass your phone’s planned data cap. In fact, using a VPN will mean you reach your data limit faster because of the VPN overhead. Read more.

What is a VPN data cap?
Some VPN services limit the amount of data you can pass through the VPN servers. This is known as a VPN data cap and it is completely separate to your cell phone provider’s data cap. Read more.

VPN Data Usage Explained

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

In other words, if you’re using cellular data and you connect to the internet through a VPN server, it will still count towards your cell phone’s monthly data cap and your service provider will still charge you for it. There’s no way around it.

NOTE: Using a VPN actually increases your data usage due to ‘encryption overheads’ (which we’ll cover in the next section).

To understand why VPNs use data, it’s worth thinking about how a VPN works.

When you use a VPN app on mobile, your phone connects to a private VPN server rather than your desired website. The VPN server then connects to the website for you, and sends you back 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. It can see that you’re connecting to a VPN server, but cannot see what you’ve instructed the server to do or where your traffic goes after reaching it.

VPN connections still need an existing internet connection to work.

For a VPN to work, you still need a functioning internet connection. This means 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:

diagram of how a VPN protects 4G data usage versus what happens 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 actually lead to more data usage than not using a VPN because of the ‘encryption overhead’. We’ll discuss this in the next section.

Alternatively, to find out whether a VPN could help you bypass your monthly data limit, skip straight to our ‘Does a VPN Give You Unlimited Data?’ section below.

Does Using a VPN Use More Data?

Screenshot of HideMyAss' Mobile App

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

According to our tests, a VPN will increase your data consumption by anywhere between 4% and 20%, depending 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:

Activity Without VPN With VPN (4% overhead) With VPN (20% overhead)
Web browsing (per web page) 1917.5 KB 1994.2 KB 2301 KB
Standard Definition (SD) Netflix Video (per hour) 0.7 GB 0.728 GB 0.84 GB
High Definition (HD) Netflix Video (per hour) 3 GB 3.12 GB 3.6 GB
Ultra HD Netflix Video (per hour) 7 GB 7.28 GB 8.4 GB

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:

side-by-side diagrams of a normal Non-VPN IP Packet and a VPN-Encrypted Packet

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.

How To Reduce Your VPN’s Data Usage

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:

VPN Protocol Overhead Our Verdict Privacy & Security Speed
WireGuard 4.53% A new VPN protocol that is quickly establishing itself as the best on the market. It’s very quick and – as our results show – very efficient. If data usage is a concern and your VPN provider supports it, we fully recommend using WireGuard. High Very Fast
IKEv2/IPSec 7.88% A good protocol for mobile users because of its ability to cope with frequent network changes. There is speculation that IPsec has been compromised by the NSA however, so be careful using it for highly sensitive data. Medium Very Fast
PPTP 8.24% Might be sufficient to evade soft data caps, but PPTP has weak and outdated security. Avoid unless absolutely necessary. Low Very Fast
OpenVPN UDP 17.23% We recommend OpenVPN as the most secure VPN protocol on the market. The UDP version is faster than TCP, but offers a less stable connection. High Fast
OpenVPN TCP 19.96% We recommend OpenVPN as the most secure VPN protocol on the market. TCP is slower than UDP and will consume slightly more mobile data. High Moderate

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.

SUMMARY

WireGuard is the most efficient VPN protocol when it comes to mobile data usage. In our tests, it increased data consumption by just 4.5%. By contrast, the industry-standard protocol, OpenVPN, uses the most data. It has an overhead of 17%-20%, depending on which transmission protocol you use.

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.

screenshot of the Split Tunneling setting in the ExpressVPN desktop app

You can turn on split tunneling in the ExpressVPN app under Preferences > General.

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.

Does a VPN Give You Unlimited Data?

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 ProtonVPN Free.

screenshot of ProtonVPN Free's promotional advertising

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.

A VPN would help 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.

SUMMARY

A VPN won’t let you overcome a ‘hard’ mobile cap – where your connection is completely cut off once you reach the monthly limit – but it can help you bypass certain forms of ‘soft’ cap.

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 circumstances and how a VPN might help or hinder you in each:

Mobile package restrictions Does a VPN help?
A ‘hard’ data cap on the amount of data you can use. No.

You’ll reach the data cap faster because of the VPN overhead.

A ‘soft’ cap, where all your bandwidth is throttled after you download 10GB (for example) in a month. No.

You’ll reach the ‘soft’ cap faster because of the VPN overhead.

A ‘soft’ cap, where streaming (for example) is limited after the first 10GB. Yes.

A VPN stops your mobile provider knowing that you’re streaming, so it won’t throttle your bandwidth. You can stream in HD again without buffering.

Roaming charges, where you pay to download or upload data in another country. No.

It doesn’t help if you connect to a VPN server in another country. You’re charged based on where your phone is connecting to the mobile network, so you won’t be able to access your domestic data allowance.

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.

Bottom Line

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.

About the Author


  • JP Jones - CTO @ Top10VPN

    JP Jones

    JP is our CTO. He has over 25 years of software engineering and networking experience, and oversees all technical aspects of our VPN testing process. Read full bio