A speed test transfers data between your device and a remote server and divides transferred bits by elapsed time. Results are influenced by server location, test duration, protocol overhead, browser limits, Wi-Fi conditions and other traffic.
Why larger tests help
Very small transfers may finish before a connection reaches representative throughput. NetVitals first attempts adaptive progress-based transfers to Netflix Open Connect targets and uses a bounded Cloudflare fallback when that path is unavailable.
Why results differ
Different services use different servers, parallel connections, algorithms and measurement windows. NetVitals labels whether the accepted result used FAST/Netflix or the Cloudflare fallback; neither is a laboratory certification.
Data usage
Throughput tests consume data. A FAST attempt is capped at 1 GB across both directions, while the Cloudflare fallback has separate 250 MB per-direction caps. Use quick checks on limited cellular plans when you only need a basic health indication.