Why are broadband speed tests different?

Due to many factors. The line your testing might be congested (meaning there's a lot of traffic between you and the service your using to test your speed). Understand that in order to perform the test a (usually large) file is send to you from the service you're using to test your speed.

Also, repeated tests may trigger speed caps on your line. Some ISPs to protect their customers against spikes in usage will throttle your connection- you're not doing yourself any favours or over customers on the providers network if everybody is performing speed tests repeatedly. Instead, space your speed tests throughout the day to get a true picture of how your speeds might fluctuate throughout the day.

Caching is where a piece of data is put closer to you so that the next time you ask for it, you can get it quicker. Now speed checking services will disable this feature- but they are not in control of your entire network. At many points between you and the speed testing service a caching server, or just your laptop can be 'caching' data to work in your flavor- but the end result would be a false positive showing a faster download speed but really it's just the effect of a cache you're experiencing.

As with any performance based test, what's important whilst testing is to establish a baseline (what is your speed like right now? What is a good speed, what is a bad speed). With a baseline you have something to optimise toward.

There's not a lot you can do regarding the wire. You can however improve your internal wiring if you think that might be the cause of a slow down. This is your responsibility. Openreach is responsible for all the wiring up to the master socket (known as a demarcation point). For help checking out your internal wiring, take a look at [exbtengineers.com](exbtengineers.com) who will come and assess your internal wiring.

If you've interested in in finding out what your expected speed would be (for example for a new connection) use our broadband availability checkerwhich gives you a best guess estimate of what your speed can be.

If you're wondering why providers simply can't give a 100% accurate speed estimate (especially for ADSL broadband) this is because you're dealing with the real world elements. Not just distance from the telephone exchange but factors such as how crowded the telephone box is at the end of your street will be a factor. Both Fibre (to the cabinet) and ADSL broadband use copper wire- copper is prone to rust and corrosion. All these factors together impact the speed you can achieve.

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