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Virtual private networks (VPNs) are the kind of tool that you don't know you need until you need one. Especially when traveling, as so many do during the summer, the best VPNs are crucial for encrypting your traffic, disguising your IP address, and limiting the risk of data exposure and surveillance while you're using public Wi-Fi.

Also: The best travel VPNs

But the main metric to consider when choosing a VPN is always going to be speed -- specifically, download speeds -- since that's what most people do on the web, whether you're streaming, saving an email attachment, installing new apps, or just about anything else. And when you're traveling, you want a VPN that won't slow you down.

We ran the top five VPNs in our lab in Kentucky through rigorous testing to find the fastest VPN for traveling. The one VPN that stood out above the rest for speed was NordVPN, which is why it earns a ZDNET Lab Awards badge. 

How we tested these VPNs

On a Spectrum cable connection, we used different Raspberry Pi configurations with unique VPN services and protocols, running a scheduled test cycle every 16 minutes to avoid network congestion and bottlenecks caused by simultaneous testing. The test cycles were staggered, ensuring that only one Raspberry Pi ran its test at any given time, minimizing cross-device interference and providing a more accurate, stable, and isolated measurement. A single test iteration yielded four metrics: download speed, upload speed, ping/latency, and packet loss.

Each test spanned 24 hours, yielding 90 data points per Raspberry Pi, per metric, per day, totaling approximately 2,160 data points per VPN service over a full six-day test cycle involving six combinations of protocols and server locations. The testing framework included OpenVPN as the baseline for comparison and a VPN-specific preferred protocol, tested against three distance-based server locations: US New York (close), UK London (medium), and Tokyo, Japan (far). 

To find the fastest VPN, we use the median for download speeds, as it is often more representative than the average and is less affected by temporary spikes, dips, or other outlier events common in internet performance testing. Gianmarco Chumbe, the manager of product testing in the lab, said that, "Generally speaking, higher median download speeds across test conditions indicate stronger throughput performance, though other factors, such as latency, variability, and protocol efficiency, also contribute to overall VPN performance."

We chose to focus on the preferred protocol method for each VPN test, since it yields the best results for each individual VPN compared to the OpenVPN baseline. In addition, we focused on travel-related aspects of these VPNs, paying closer attention to server speeds in locations outside the US, since travel season is a timely metric for many right now. 

The results

As you can see from our interactive graphics for the preferred protocol London location (Fig. 2) and Tokyo location (Fig. 3), NordVPN had the fastest download speeds compared to the starting speed. For reference, NordVPN was connected to its preferred protocol, NordLynx. 

Read the review: NordVPN

Chumbe said that it was surprising to see how dramatically NordVPN's performance differed between running on OpenVPN and NordLynx, its proprietary protocol. 

"NordLynx consistently performed among the strongest options, particularly for long-distance server connections, where it achieved some of the highest download speeds observed during testing," he said. 

Other VPNs that performed well in our preferred protocol testing were Surfshark, which tied with NordVPN for fastest download speed in Fig. 3 and was the fastest in Fig. 1. In addition, IPVanish saw promising speeds across all locations when it ran on the WireGuard protocol. 

(Editor's note: IPVanish is owned by Ziff Davis, ZDNET's parent company. For more, see our Editorial Guidelines.)

Notably, ExpressVPN had some of the slowest download speeds on the preferred protocol tests when using its Lightway-UDP protocol. This does not mean that ExpressVPN is a slower VPN, but that other protocols, such as OpenVPN, might work better with it. 

As a tip, almost all of the VPNs we tested offer a free trial — anywhere from 7 to 30 days — or a free money-back guarantee, so you can always sign up for a VPN before your trip and then cancel when you're home. 

Also: The best free VPNs: Expert tested and reviewed 

Our test results might differ from your experience, depending on the protocol you are using and the type of internet connection you have. However, as a general baseline, our testing provides an expert analysis of how these VPNs perform in different locations and countries, no matter where your travels take you this summer.