How this speed test works

Pressing start runs three measurements, in order, from this browser to this server. The page works the figures out on your device. They are not written to a database.

Latency and jitter

The browser requests a tiny response, one request at a time. The first request is a warmup and is thrown away. The next 10 round trips are kept. Ping is the median of those round trips, in milliseconds. Jitter is the average change from one round trip to the next.

Median is the middle sample, so one unusually slow or fast request does not set the number on its own.

Download

The browser opens 6 downloads at the same time. The server sends random data and tells caches not to store or compress it. After 10 seconds the browser stops, counts the payload bytes it actually read, and converts them to megabits per second. One Mbps is one million bits per second. Overhead from the protocols around that payload is not added back in.

Upload

The browser then sends random data on 4 uploads at once, for 10 seconds. The server reads the data and discards it. The browser counts the bytes it handed to the connection. Nothing from the upload is kept as a file.

The short note under the result

That note compares your download with the single-stream figures Netflix publishes, and your upload with the video-call figures Zoom publishes. The sources, and the actual numbers, are on what speeds you need. Latency is described as a rough guide, because there is no universal "good ping" that fits every game and every call. The note is about this test. It is not a promise that a particular service will look perfect.

What a single test cannot tell you

It cannot see the package you pay for, the line into the building, or a fault on the provider's network. It cannot be faster than both your connection and this server. If this server is busy, or a long way from you, the result sits below the speed of your line.

It is one moment. Run it more than once, with other downloads paused, if you want a fairer picture. Compare Ethernet and Wi-Fi before you blame the package. What affects speed goes through those cases.

This is an independent test. It is not an Ofcom test, it is not affiliated with Ofcom, and it is not run by an internet provider. The site is operated by Outbound BPO Ltd.

The privacy page says what happens to the test traffic. To write to the operator, use the contact form.