Does a VPN Use More Data?

Browsing the internet with a VPN uses more mobile data than not using a VPN.

I can also confidently tell you exactly how much more data a VPN uses, as I’ve performed a rigorous experiment to measure how much extra bandwidth each VPN protocol consumes compared to a standard internet connection.

According to my VPN data usage tests, a VPN increases your data consumption by anywhere between 4.5% 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:

Activity	Without VPN	With VPN (4.5% overhead)	With VPN (20% overhead)
Web browsing (per web page)	1,917.5 KB	2,003.8 KB	2,301 KB
Standard Definition (SD) Netflix Video (per hour)	0.7 GB	0.732 GB	0.84 GB
High Definition (HD) Netflix Video (per hour)	3 GB	3.14 GB	3.6 GB
Ultra HD Netflix Video (per hour)	7 GB	7.32 GB	8.4 GB

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 an illustration of how the payload data is reduced in VPN vs non-VPN packets:

To understand why VPNs use data, let’s 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, making you much harder to identify.
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 can’t 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 is going from that point onward.

VPN connections still need an existing internet connection to work.

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 can’t 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.

As my tests showed, using a VPN actually leads to more data usage than not using a VPN, because of the ‘encryption overhead’.

Yes, but the VPN itself uses very little.

A VPN has to send occasional keepalive packets to stop the connection dropping, which keeps your connection open through your carrier’s NAT (or your router’s firewall, if you’re on WiFi). With WireGuard these packets are tiny – roughly 60 bytes of data, sent every 25 seconds by default. This works out to single-digit megabytes over a full month. OpenVPN pings more frequently, so its idle cost is higher, but it’s trivial next to anything you’d actually notice.

Reconnections cost a little more. Every time your phone wakes, switches between WiFi and cellular, or moves between cell towers, the VPN has to renegotiate the tunnel. IKEv2/IPSec handles this most gracefully, which is one reason I recommend it for people who are constantly on the move.

It’s worth remembering that your your phone is never truly idle. Push notifications, email sync, cloud photo backup, and background app refresh all keep sending and receiving whether you’re looking at the screen or not – and the VPN applies its overhead to that traffic just as it does to anything else. An always-on VPN quietly costs you data, and it’s proportional to how chatty your apps are rather than to the VPN itself.

If you’re trying to make your cellular plan’s allowance last, turning off background app refresh will save you far more than turning off your VPN.

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

1. Choose the right VPN protocol

VPN protocols govern how the VPN client (e.g. your smartphone) communicates with the VPN server. Some are more data-efficient than others.

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

VPN Protocol	Overhead	Verdict	Privacy & Security	Speed
WireGuard	4.53%	Newest, fastest, and most efficient and secure VPN protocol. I highly recommend WireGuard for data-conscious users.	High	Very Fast
IKEv2/IPSec	7.88%	A good protocol for mobile users as it smoothly handles frequent network changes. Be cautious using it for highly sensitive data as IPSec may have been compromised by the NSA.	Medium	Very Fast
PPTP	8.24%	PPTP has weak and outdated security. Avoid unless absolutely necessary.	Low	Very Fast
OpenVPN UDP	17.23%	OpenVPN is a highly trusted, secure VPN protocol. UDP is faster than TCP, but is less stable.	High	Fast
OpenVPN TCP	19.96%	OpenVPN is a highly trusted, secure VPN protocol. TCP is slower than UDP and will consume slightly more mobile data.	High	Moderate

Generally, more data-efficient protocols are faster. For instance, WireGuard and IKEv2/IPSec are some of the fastest VPN protocols around.

You’d expect more secure protocols to carry bigger overheads, but my findings don’t bear that out. My results show WireGuard is every bit as secure as OpenVPN yet far more efficient, while PPTP is the least secure and uses more data than IKEv2/IPSec.

2. Turn off the VPN

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

I 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.

3. Use split tunneling

Some VPN services offer a specialized feature, known as VPN split tunneling, which lets you specify which apps and services you want to route via the VPN connection and which you want through your normal carrier connection.

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

Using a VPN won’t overcome your cell phone plan’s data limit or provide unlimited data. In fact, as my findings above show, VPNs consume more data due to overhead.

VPN companies advertising ‘unlimited bandwidth’ or ‘no data cap’ refer only to their service, not your cell phone’s data limit. Premium VPNs typically offer unlimited bandwidth, but most free VPNs impose their own data caps. Proton VPN Free is the rare exception, with no data cap at all.

Cellular providers sometimes apply ‘soft’ caps, slowing specific high-bandwidth activities after reaching a data threshold. A VPN can bypass this type of throttling by encrypting your traffic, making it unidentifiable to the provider.

However, if the ‘soft’ cap applies to all traffic, and not just to certain activities, then a VPN won’t help.

Unfortunately, a VPN can’t help you avoid data roaming charges abroad. Charges are based on the cell tower location, not your VPN server location.

Here’s how VPNs affect different mobile package restrictions:

Mobile package restrictions	Does a VPN help?
‘Hard’ cap on the amount of data you can use.	No. You’ll reach the data cap faster due to VPN overhead.
‘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 due to VPN overhead.
‘Soft’ cap, where streaming (for example) is limited after the first 10GB.	Yes. A VPN prevents your mobile provider from identifying streaming traffic, so it won’t throttle your bandwidth.
Roaming charges, where you pay to download or upload data in another country.	No. Charges are based on phone location, not VPN server location.