How do broadband speed tests work?

Broadband speed tests are used to confirm the quality of your internet connection. The speed tests are run by visiting a web page. There are hundreds of speed tests available online from servers all over the world. Most ISPs also have a speed test so their customers can check their connection.

How Download and Upload Speeds Are Calculated

All broadband speed tests follow the same basic process:

1. You visit a page on the broadband speed test server.
2. A Java applet is copied from the server and executed.
3. The applet downloads data from the server and records time taken.
4. Data is uploaded to the server. Again the time is recorded.
5. The server calculates your connection speed using the recorded times.

How long it takes depends, of course, on your connection speed and the test server location. If the test server belongs to your ISP it will report higher speeds than if the test server is somewhere else in Australia, or if the test server is overseas. This is because the further away a server is from your computer, the more intermediate equipment (routers, switches, gateways) it has to pass through, each reducing the connection speed by adding their own small delay.

Latency and Round Trip Time

Broadband speed tests also report latency or Round Trip Time. This is given in milliseconds and measures how long it takes for the data to travel from your computer to the server. The lower that this number is, the better.

If you play server-based games or use Voice over IP (VoIP) to make calls you want the latency time to be as low as possible. A time of 100-150 milliseconds or smaller is necessary to achieve the best connection quality.

If My Connection is So Fast, Why Are Some Sites Slow?

The thing about broadband speed tests is that the servers they run on need to be very fast with very high bandwidth connections - much faster than the ADSL and broadband cable connections they are measuring.

Most web sites, except huge ones like Google, Facebook or Yahoo, will have slower connections and slower servers simply because it is cheaper.

So Why Run A Broadband Speed Test?

Even though you will only rarely see the kind of speed reported during a broadband speed test in your normal daily internet use, running the test occasionally is a good way to check everything is working as it should.