The average UK household is receiving just half of the advertised broadband speed with users paying for up to 38 megabits per second, but receive only 19Mbps.

The research by campaign group Which? showed the magnitude of the gap ahead of guidelines which come into effect next week.

From Wednesday, speed claims in broadband ads should be based on the download speed available to at least 50% of customers at peak time, as opposed to the current requirement of at least 10%.

Its speed tests found that overall, the faster the speed advertised, the greater the gap from the actual speed recorded.

As an example, consumers paying for a package of ‘up to 200Mbps’ were only able to get average speeds of 52Mbps – just 26% of the speed promised.

But even customers on standard broadband packages, advertised as being ‘up to 17Mbps’, were receiving an average speed of just 6Mbps – a third of the claimed speed.

The closest match between claim and reality was for those on ‘up to 50Mbps’ broadband deals. Here users received an average of 35Mbps, 70% of the advertised speed.

Alex Neill, Which? managing director of home services, said: “This change in the rules is good news for customers, who have been continuously let down by unrealistic adverts and broadband speeds that won’t ever live up to expectations.

“We know that speed and reliability of service really matter to customers, and we will be keeping a close eye on providers to make sure they follow these new rules and finally deliver the service that people pay for.”

‘Results rather odd’

Dan Howdle, consumer telecoms analyst at broadband advice site, Cable, said the results don’t tally up with the latest Ofcom testing figures which revealed that a 200Mbps connection averaged 92% of the advertised speed at peak times.

“With such a large disparity between Ofcom’s results and those of Which?, I believe something could be amiss. One possible explanation might be if measurements were to be taken over wifi (rather than over a LAN cable) – this would have the potential to show the much slower averages measured by Which?.

“Wifi, while capable of these speeds on paper, tends to be slowed down considerably (compared to a LAN cable) in your typical urban environment thanks to signal interference and architectural considerations. Whatever the cause, Which’s results are at odds with those of the regulator, as well as a multitude of other sources.”

In response, Which? explained that for its research, it relied on self-selection from the customer, so the user told the tool the advertised speed and median download speed.

A spokesperson added Which? encourages users to measure their speed using an ethernet cable so they can check the speed at the router. However, it noted that some tests may be conducted over wifi. Where users do use wi-fi, Which? asks users to position themselves as close to the router as possible to minimise any effect on speed.