How UK broadband speed tests work

Short answer: a speed test measures a sample of your connection performance at that moment. It is useful for trends and troubleshooting, but a single run is not a full diagnosis of your line.

What this test measures

• Download speed (Mbps): how quickly data is delivered to your device.
• Latency (ms): how fast your connection responds.
• Jitter (ms): how stable latency remains between checks.

How to interpret results correctly

Throughput tells you how quickly files and streams can load. Latency and jitter tell you how responsive and stable the connection feels for real-time tasks such as calls and gaming. You need all three to judge quality.

Why two tests can show different numbers

• Wi-Fi signal quality changes with distance, walls and interference.
• Other devices can consume bandwidth in the background.
• Peak-time network demand can affect evening performance.
• Device/browser limits can cap what a test reaches.

Best-practice testing method

1. Run one test on Ethernet if possible, then compare with Wi-Fi.
2. Run multiple tests at different times, including evening busy hours.
3. Keep the same device and location when comparing runs.
4. Record your baseline before changing package or equipment.

UK consumer context

Ofcom advises consumers to test more than once and vary testing times. Ofcom also explains speed rights under its broadband speeds guidance and code of practice. See Ofcom practical speed tips and Ofcom broadband speeds guidance.

Next steps: check what is good latency, learn what jitter means, or follow broadband troubleshooting.