How does Cloudflare’s Speed Test really work?

Cloudflare’s Speed Test runs on Cloudflare’s own global network, with the test results generated by the Network Quality API and routed to the nearest data centre using anycast, according to Cloudflare. Instead of saturating a connection, the test sends predefined data blocks a fixed number of times to assess quality under realistic usage, and then displays results as box-and-whisker plots showing observed ranges and percentiles.

It measures the time to establish a connection, the transfer time, and includes loaded and idle latency, jitter, and packet loss, with the final Aggregated Internet Measurement (AIM) score summarising overall performance. The test runs primarily from an end-user device within the browser, so results reflect the combined performance of the path to content delivered by Cloudflare’s network, not just the ISP.

All results from Cloudflare’s Speed Tests are anonymised and published to Measurement Lab’s public dataset, and are also accessible via Cloudflare Radar; the engine is open source and the project collaborates with partners such as UNICEF’s Giga initiative and Orb. Cloudflare plans to expand measurements and capabilities through 2026 to enable more detailed analysis and broader third-party use. 27 October 2025