Best and worst UK postcodes for mobile coverage revealed

Parts of Wales and South West England have been named the worst mobile not spots in Britain.

Despite the technological advances, many people still suffer from patchy or even no mobile signal.

The big four mobile networks - EE, O2, Three and Vodafone - claim their 4G networks cover around 99% of the UK. But new research from consumer group Which? and data firm Opensignal reveals what service you get can depend where you are, just down to a very local level.

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A network quality map uses real-world data from consumer mobile handsets to create a percentage score for how consistent the signal is in each postcode area in the year to August 2025.

SA70 in Tenby - a popular Welsh seaside tourist destination - was named the worst postcode for mobile network quality, with mobile users only experiencing a good connection 54.3% of the time. But even this included a range from 71% for EE customers to just 38% for those with Three.

LD1 in Llandrindod Wells was ranked the second-worst postcode for mobile network quality, with a score of 54.8% overall. Three was the worst network, with its customers experiencing a good connection just 41% of the time. O2 customers enjoyed the best experience, with a score of 66%.

In England, TA5 in Taunton, Somerset, and TR4 in Truro, Cornwall, had the worst postcodes for network quality - with scores of 56% and 57.8% respectively. O2 was the patchiest network in both areas, while EE provided the best connection.

The research found those in bigger cities - including London, Nottingham and Glasgow - enjoyed the best mobile coverage. SE11 in London - covering parts of Kennington and Vauxhall and just across the Thames from Parliament - and NG3 in Nottingham tied for the postcodes with the best quality mobile coverage, with a score of 87.8%.

Natalie Hitchins, Which? head of home products and services, said: “This research shows just how dramatically the quality of mobile coverage can vary across the UK. Choosing the right provider can mean the difference between seamless coverage or constantly battling to make a call from the comfort of your own home.

The Which? mobile quality map is taken from more than 17 million network tests taken across the UK over the past 12 months from users of Opensignal apps and is powered by the same data as the Ofcom Map Your Mobile tool.

Top 10 postcodes, and average network score

• SE11 - London - 87.8%
• NG3 - Nottingham - 87.8%
• RM5 - Romford - 87.5%
• IG2 - Ilford - 87.3%
• WD24 - Watford - 86.8%
• SW3 - London - 86.8%
• SE27 - London - 86.8%
  
• GE13 - Glasgow - 86.8%
• BD3 - Bradford - 86.8%
• SM3 - Sutton - 86.5%

Bottom 10 postcodes

• SA70 - Tenby - 54.3%
• LD1 - Llandrindod Wells - 54.8%
• TA5 - Taunton - 56%
• TR4 - Truro - 57.8%
• DY13 - Dudley - 58.5%
• SA13 - Swansea - 60%
• ME19 - Medway - 60.8%
• TR27 - Truro - 60.8%
• TR18 - Truro - 60.8%
• IP17 - Ipswich - 61.3%