In a central London hotel, a classic red telephone box weighing 104kg hangs from three smartphones. This is not art or immersive theatre but the latest stunt in the race to create the world’s thinnest mobile phone.
It was part of the launch for a new foldable phone, the Magic V5, made by the Chinese company Honor. Only 4.1mm thick when unfolded and 8.8mm closed, the phone — which is only slightly thicker than its charging port — pushes sleekness to the limit.
The company was keen to dispel the notion that the phone would bend or snap more easily — and it set a Guinness World Record for, essentially, hanging something heavy from a phone.
The stunt with three phones earned Honor a Guinness World Record
The phone at the top rang to show it was working
Honor also took the “skinniest foldable” title from Samsung, whose Galaxy Z Fold7 is 4.2mm thick when open, and 8.9mm closed. The Korean company had itself snatched it from Oppo, another Chinese company, whose Find N5 measured 4.21mm when open and 8.93mm when closed (“thinner than a pencil”).
It is not only foldables that are getting thinner. Standard “slab” phones are taking digital Ozempic, too. Samsung’s Galaxy S25 Edge, launched this year, is 5.8mm thick and Apple is putting the chunky iPhone on a diet next month when it launches a 5.5mm version, according to Bloomberg. As Ben Wood of CCS Insight said, 2025 has been “the year where thin is in”.
In the growing foldable market, phone companies are keen for their products to be no thicker than a standard phone so they can justify premium prices for the fold-out screen that effectively gives users a second device, a tablet. The Magic V5, which costs £1,699, is slightly thicker than the iPhone 16 Pro Max.
Francisco Jeronimo, an analyst at IDC, said: “We are coming to a point where there’s no compromise in terms of weight and thickness of a device if you decide to buy a foldable. Until last year, there were compromises. Now, there aren’t: a huge battery, huge screens, the devices are strong … making a very strong case for consumers. You can have a tablet in your pocket and it looks like a very normal smartphone.”
The Magic’s battery capacity is a third greater than its Samsung rival, and technology advances transferred from the electric car industry have helped companies pack more power into smaller spaces. A key development has been the introduction of silicon, which is much better than graphite at storing energy, into the mix of the battery.
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Yan Zhao, a founder and chief technology officer of the UK start-up Breathe Battery Technologies, said: “It used to be that we were moving on incremental capacity gains every year — like 1 per cent, 2 per cent — with this [battery] technology. I think it’s jumped into 5 per cent steps [with silicon]. I think it would probably give you 50 per cent more at some point if you solve a bunch of issues with it.”
The Magic V5 boasts 15 per cent silicon in its battery (and 25 per cent in the Chinese version) but, Zhao said, there is a trade-off: the battery’s lifecycle. “The more you use the bits you put in to get extra capacity, the quicker it dies,” he said. “So they probably have algorithms inside the phone to say, ‘If you don’t have to use it, don’t use it’.”
The case for thinner slab phones is harder to make, according to the influential reviewer Marques Brownlee. He said on YouTube that the Samsung Galaxy Edge “demands attention” but “nobody really asked for thinner phones”.
He added: “They look cool, sure, and they make for flashy commercials. But what most people actually want is thicker phones with smaller camera bumps and significantly bigger batteries. Universally, more battery life wins over thinness.” The Edge, he said, has 25 per cent less battery longevity than the S25 and does not have a telephoto lens.
Foldable phones effectively give the user an extra device: a tablet
Apple’s rumoured skinny iPhone, which some are calling the “Air”, would reverse a design trend that has resulted in thicker devices since the iPhone 6 in 2014 (6.9mm). That will help stop the phones being “samey”, according to Wood.
“It means for the first time in several years you’ll be able to walk into a pub and put the phone on the bar and people will go, ‘Is that the new iPhone?’,” he said. “I don’t believe that ‘thin’ is enough to reinvigorate the smartphone market, but it certainly provides a new story and marketing line for these companies.”
Apple considered dropping the charging port altogether, according to Bloomberg, but balked. Industry relies on it for interrogating and repairing the phone, but Jeronimo believes that with wireless charging becoming more pervasive, the port’s days may be numbered.
“The problem with becoming even slimmer is that at some point it will break,” Jeronimo said. “I think we’ve got to a point where it’s very hard to become slimmer than what we have today.”