The average broadband access download speed UK users experienced rose 5% to 6.2Mbps, but this is less than half the average headline speed they pay for, communications regulator Ofcom says.
Ofcom's fourth annual report into broadband speeds is based on 765 million tests that were run across a panel of 1,710 UK residential broadband users by research partner SamKnows between 1 November 2010 to 15 December 2010.
"We found that average download speeds remain well below the advertised speeds which some ISPs continue to use: the average download speed for all UK residential connections of 6.2Mbps compares to an average advertised speed of 'up to' 13.8Mbps, equivalent to 45% of the advertised speed," Ofcom said.
Users on "up to" 20Mbps or 24Mbps ADSL packages received just 29% of the advertised headline speeds, Ofcom said, while users on "up to" 8Mbps or 10Mbps ADSL services received just 42%.
Just 14% of customers on "up to" 20Mbpss or 24Mbps ADSL services received average download speeds of over 12Mbps, and 58% received 6Mbps or less, Ofcom said.
BT's "up to" 40Mbps fibre to the cabinet (FTTC) service, currently available to 15% of UK premises, is increasing access speeds, with downloads averaging 31.8Mbps, 80% of the advertised headline speed, Ofcom said.
The regulator said cable and fibre services were faster than ADSL and much closer to advertised speeds. Virgin Media's "up to" 10Mbps cable service delivered average speeds of 9.6Mbps, 96% of the advertised level and "significantly faster" than the average speeds delivered by 20Mbps or 24Mbps ADSL services, it said.
This was also true for higher levels. Virgin Media's 20Mbpss cable service averaged 18.0Mbit/s (90% of advertised speeds) and its "up to" 50Mbps service averaged 45.6Mbps (92% of the advertised 'up to' speed).
Ofcom has recommended that the Advertising Standards Authority, which looks into misleading advertising claims, change its policy to require internet service providers include a more realistic assessment of the typical speeds users can expect. Users on 8Mbps ADSL packages could expect download speeds of 2-5Mbps; those on 20-24Mbps ADSL package could expect 3-9Mbps.
Ofcom said upload speeds have become more more important to users and are now "a source of differentiation" among ISPs. BT's 40Mbps FTTC Infinity was advertising upload speeds of "up to" 10Mbps and achieving an average of 7.8Mbps.
Virgin Media's "up to" 50Mbps delivered average upload speeds of 2.8Mbps, it found, but all other ISP packages managed less than half this, Ofcom said.