Ookla Name Three UK Fastest and O2 Slowest for 5G Mobile Broadband in H1 2025
Network testing giant Ookla, which collects data from consumers via their popular broadband Speedtest.net service, have released their latest Q3-Q4 2025 (H2) study into the speed of 5G based mobile broadband networks across the United Kingdom. The results reveal that Three UK continues to be the fastest provider, while O2 (Virgin Media) was the slowest.
The catch is that mobile broadband performance can be a very difficult thing to pin down because users are always moving through different areas (indoor, outdoor, underground etc.), using different devices with different capabilities and the surrounding environment is ever changeable (weather, trees, buildings etc.). And that’s before we consider the other issues, such as network capacity and varying spectrum use at different cell sites. But these caveats are true for all the operators in this study.
Overall, Three UK once again secured the top spot with a “Speed Score” of 53.46 (down from 55.17 in H1), median average download speeds of 214.02Mbps (down from 227.77Mbps) and median upload speeds of 13.08Mbps (unchanged). The full results below also include some extra figures for all of the major mobile operators.
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Just to be clear, Ookla’s Speed Score is produced using data from various metrics, including the 10th, 50th, and 90th percentiles of download and upload throughput and loaded latency. Different aspects of these have different weightings in the final score, for example, download speed is most relevant (70%) to the end result, while upload speed counts for 20% of the weighting and latency just 10%.
Fastest UK 5G Operators by Speed Score – H2 2025 (H1 2025)
1. Three UK – 53.46 (down from 55.17)
2. Vodafone – 43.05 (down from 45.04)
3. EE (BT) – 36.73 (down from 38.46)
4. O2 (Virgin Media) – 30.70 (down from 31.13)
We expect the results for Three UK and Vodafone to slowly change as they bring their respective networks together following the recent merger, but for now Ookla still list them as separate networks.
Mark is a professional technology writer, IT consultant and computer engineer from Dorset (England), he also founded ISPreview in 1999 and enjoys analysing the latest telecoms and broadband developments. Find me on X (Twitter), Mastodon, Facebook, BlueSky, Threads.net and Linkedin.
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