Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.

In 2018, CAP introduced new Advertising Guidance entitled ‘Broadband speed claims’, which also applies to mobile data services. It points out that different customers of the same provider can achieve different broadband speeds, and that such variations in speed can be negligible or highly significant depending on myriad factors. Whilst it focuses on claims on download speeds (as they are referred to more frequently in marketing), claims about upload speed should also conform to the principles where relevant.

Numerical speed claims: overview

Numerical speed claims: substantiation

Location specific claims

Non-numerical speed claims

Numerical speed claims: overview

The guidance makes clear that speed claims must be based on the actual experience of users. Advertisers should be able to demonstrate that a reasonable proportion of customers can achieve the speeds claimed in their ads.

Advertisers making numerical speed claims should be able to demonstrate that the speed quoted is achievable for at least 50% of the relevant customer base at peak time (defined by Ofcom as between 8 and 10pm). When advertising speeds achievable by at least 50% of their customers, the speed should be described as ‘average’, or similar. If the speed has not been measured nationally, this should be made clear (i.e. by being targeted at a particular area). Providers should include a statement urging consumers to check their likely speed independently. In 2022, Virgin Media’s measurement of the average speed of their Gig1 fibre service, and the presentation of their associated claim in the ad, were deemed in line with the guidance – although the information available for verification was found to be lacking (Virgin Media, 4 May 2022).

If there are any significant factors as to why certain customers are unlikely to be able to achieve the speed stated, such factors will be considered material information and should be stated in the ad. Evidence of the significance of a given factor will be considered on a case-by-case basis. Qualifications explaining the likely effect of a factor on a consumer’s ability to achieve the advertised speed should be prominent, included in the body copy of the ad, and should be explained in easily understood terms.

In some circumstances, further qualification will be needed. If a significant proportion of consumers receive a maximum speed that is so much lower than the headline speed that they cannot carry out normal online activity, for example streaming content, advertisers must include further qualifying information, such as:

“X% of our customers receive speeds below YMbit/s”

“X% of our customers receive speeds above YMbit/s”

“X% of our customers receive speeds between YMbit/s and ZMbit/s”

Numerical speed claims: substantiation

Advertisers can gather and process data themselves, or use an independent body, providing the data supports the speed claims made. Speed claims should be based on user’s genuine experience and usage and will be assessed on a case by case basis. Further detail on substantiation is available in the Advertising Guidance.

Location specific claims

Internet providers sometimes offer customers the capacity to check speeds for their specific postcode online. As the ASA emphasised in a ruling against BT, if figures are an estimate, this should be stated clearly. In the relevant ruling, the ASA considered that consumers would interpret ‘Your Stay Fast Guarantee’ to be referring to the minimum broadband speed BT would commit to provide to the consumer’s address. Given the guaranteed speed in this context was actually a reference to an estimate, that was subject to revision, the ad was deemed misleading (British Telecommunications plc t/a BT, BT Sport, 22 December 2021).

The issue with implying that estimates were exact figures, rather than speculative amounts, was also considered, albeit in the context of pricing rather than speed, in a 2020 ruling involving Telefonica (Telefonica UK Ltd t/a O2, 18 March 2020).

Non-numerical speed claims

Speed claims using words instead of numbers (i.e. non numerical speed claims), which are likely to significantly influence a consumer’s expectation of the speed of an advertised service, will be assessed on a case-by-case basis, but should, where relevant, include any further necessary qualifying information.

‘Superfast’ is commonly used in relation to new technologies such as fibre-optic broadband to distinguish services from speeds previously achieved by ADSL. Ofcom currently defines 'superfast' as technology capable of providing speeds equal to or greater than 30 Mbit/s. Advertisers should ensure that any references to superfast do not exaggerate the capabilities of the network.

In 2019, the ASA investigated Sky’s use of this term. A complaint for a Sky ad which stated "superfast in the kitchen" was not upheld because it was found consumers would understand the claim “superfast” to mean speeds which were faster than ADSL (‘standard’) broadband. The ASA said consumers would appreciate that while they could expect to receive superfast speeds at the router, Wi-Fi speeds on their devices could not be guaranteed and would reduce the further they were from the router. It was decided consumers would understand “superfast in the kitchen” to mean that Sky offered a broadband service which provided superfast speeds, and whilst they might be able to receive such speeds in their kitchen, those speeds would be dependent on how far the kitchen was from the router (Sky UK Ltd, 06 March 2019).

There is currently no fixed definition of “superfast” in relation to mobile network speeds. Advertisers have previously used it in reference to the comparative increase in speeds of 4G versus 3G. However, the ASA has ruled that without qualification, using the claim 'Superfast mobile broadband' could lead consumers to understand that the "superfast" definition that applied to fixed line broadband could also apply to 4G (when the speeds are significantly slower). However, the ASA ruled that the same claim in a TV ad was acceptable, as the average 4G speeds were clearly stated in on-screen text, so the ad did not imply that speeds available were, at a minimum, the ‘superfast’ speeds available for fixed line broadband (Everything Everywhere Ltd t/a EE, 31 July 2013).

Advertisers should also be wary of suggesting that slower networks have comparable speeds. For example, the ASA ruled that the term "3.9G” misleadingly implied that a network had speeds very close to that of 4G (Hutchison 3G UK Ltd t/a 3, 22 January 2014).

Similarly, the ASA investigated the name of a home broadband provider, 6G Internet, and found that consumers would expect the provider to use a next generation 6G internet technology, when this was not the case. ‘6G Internet’ was deemed misleading (6G Internet Ltd, 16 August 2023). A similar ruling involved Vodafone. In that instance, the ASA found that marketing ‘Gigafast broadband’ as available ‘from £23’, when the offering available at £23 provided speeds of 100 Mbps only, was contrary to the Code (Vodafone Ltd, 17 April 2019).


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