If you are with BT for your broadband/adsl max service, this is the link for their service speedtester.
Enter your telephone number (including area code) and click start.

 BT speedtester (Opens in new window)

If you are having problems with your download speed, its worth cutting and pasting the results onto a notepad file and saving to your desktop, then you have references to quote when reporting a fault.
Try running the test at different times of the day.