How does the speed test work?

The speed test runs in your browser, using Measurement Lab (M-Lab)'s open-source ndt7 test (Apache License 2.0). When you click Start the test, your browser:

1. asks M-Lab which of its test servers is nearest to you,
2. downloads data from that server for about 10 seconds, then
3. uploads data to it for about 10 seconds,

all over an encrypted connection.

The download speed is the data your browser received divided by the time it took. The upload speed is what the M-Lab server reports receiving. The latency is the shortest round-trip time the server measured during the test.

Our server isn't involved in the test, and your results aren't sent to us. M-Lab publishes every test result, including your IP address, as open data for internet research; see M-Lab's privacy policy.

Results vary from one test to the next: Wi-Fi, other devices on your network and the distance to the test server all affect them.

Last updated: September 29, 2026 (12:47 AM GMT)