Frequently asked questions about ZDNet's speed test for broadband connections
Is your broadband fast enough? Are you getting what you've paid for? Find out with our Broadband Speed Test. Just pick your location and wait a few seconds for the results.
For better results, run the test a few times. And you can compare your speeds with friends on other ISPs, or at different times of the day, to see whether you're getting the best value you can from your broadband subscription.
When you click on the test, it starts transferring a 3MB file from a datacentre near you. The data is random and not cached, and the transfer is timed.
If you are using a mobile connection, please make sure your data plan will not incur excessive charges for a 3MB download. In general, UK users on 'unlimited' data tariffs should not have a problem, but we do not recommend you run this test while roaming away from your home country.
Your broadband connection is shared with tens - sometimes hundreds - of other users at your ISP before it is connected with the ISP's own links into the internet. During periods of high demand, which tend to be early evenings, this can cause congestion.
The broadband speed test is designed to reflect web traffic over other internet usages. Some ISPs monitor and slow down non-web traffic of various kinds, giving different speeds for different programs: also, other software behaves differently from web browsing and can be more or less sensitive to performance bottlenecks.
Check out our tips for increasing broadband performance. Another useful thing to do if you have a laptop is to try connecting to a friend's broadband connection and see whether your experience is still slow - in which case your computer, not your connection, is at fault. If that doesn't help, collect speed results over a week or so, so you have some ammunition when you phone your ISP's customer services. If they can't or won't help, take your custom elsewhere.