How to read a speed test result

A speed test gives you four numbers. Most people read one of them, and it is usually the least interesting.

Ping is a round trip, not a speed

Latency is the time for a small request to reach the server and come back, in milliseconds. It is measured with eight quick requests, and the first is thrown away — that one carries connection setup cost rather than steady-state latency, and leaving it in either flatters or punishes the result depending on whether the connection happened to be warm.

Jitter is the number that ruins calls

Jitter is how much consecutive latency samples differ from one another, averaged. A connection at 40 ms with 3 ms of jitter feels smooth. The same 40 ms with 60 ms of jitter stutters, because packets arrive bunched and the receiver has nothing to play while it waits for the gap.

Under 30 ms is comfortable for calls and games. If your bandwidth looks healthy and meetings still break up, this is the number to look at.

Download and upload are measured in parallel

Both figures come from several simultaneous streams — four for download, three for upload — rather than a single one. That is deliberate. One connection rarely saturates a modern link: it ramps up gradually and backs off on any packet loss, so a single-stream test consistently under-reports what the line can do. Parallel streams measure the capacity you actually get from a browser loading a page or a backup client working through a queue.

Megabits, not megabytes

Speeds are quoted in megabits per second; your file manager counts megabytes. Divide by eight. A 100 Mbps connection tops out around 12.5 MB/s, so a 1 GB download taking eighty seconds is the line working perfectly rather than failing you.

Why you never see the number on your bill

Your plan speed is what arrives at the router. The test measures what reaches this tab, after:

• Wi-Fi, which routinely halves throughput and does far worse two rooms away.
• Other devices sharing the line while you test.
• A VPN, which adds a detour and encryption overhead.
• Distance to the test server, and the state of everything in between.

Test over Ethernet with other traffic closed if you want to know what the line can do. Test on Wi-Fi from the sofa if you want to know what your evening will feel like. Those are different questions and both are worth asking.

Run it more than once

A single run catches whatever the network was doing in that ten-second window — including the download that started thirty seconds ago in another tab. Recent runs are kept on your own device, so the useful comparison is against yesterday at the same hour, not against the number on the advertisement. If you want to know what is reaching you right now, run one — and check what your connection reports about you while you are there.