Despite none yet being available to buy, ultra-thin phones seem to be the big tech trend of 2025, with the iPhone 17 Air and Samsung Galaxy S25 Edge due alongside handsets built by Chinese manufacturers like Honor and Tecno.
For thin-phone skeptics, the worry is what this obsession with thinness will do to battery life. It appears that fear is at least somewhat justified, as a new leak has revealed Samsung’s entry will be 100mAh smaller than the regular Galaxy S25.
The Tech Outlook spotted two battery listings for the Samsung Galaxy S25 Edge which carry a rated value of 3,786mAh. Even assuming that’s a rated value and the typical value will be 3,900mAh as tipped elsewhere, that’s still a worrying development.
The regular Samsung Galaxy S25 carries a 4,000mAh battery, and although it fared pretty well in our battery test, lasting for 15 hours and 43 minutes of website browsing over a cell connection, it has a relatively small 6.2-inch screen.
Leaks suggest the Galaxy S25 Edge will have half an inch more screen, matching the 6.7-inch Samsung Galaxy S25 Plus. This also did well in the same battery test, achieving a time of 16:55 before running out of juice. But while phones with bigger screens usually compensate with a larger battery, the S25 Edge won’t have that — in fact, it’ll be 1,000mAh smaller than the 4,900mAh Plus model.
Fatal flaw or mild inconvenience?
All of this adds up to a phone that may be a tricky sell to power users. This could be offset by support for fast charging, but rumor has it that the S25 Edge will only match the 25W wired charging of the regular model, and not the 45W speeds of the Plus and Ultra versions.
But to keep things in perspective, the battery life on the regular S25 is better than most people need.
Smartphone owners have gotten used to the nightly charging ritual associated with ownership, and as long as it gets through a day, most people won’t mind. It’s only when it badly undershoots that low-bar aim — like the Samsung Galaxy Z Flip 3 — that people are truly disappointed.
There’s also an argument that says ultra-thin phones simply aren’t aimed at power users, or those who obsess over the minutia of specs and comparison tables.
The only real advantage is weight and aesthetics, neither of which matter all that much to people looking to eke as much life out of their handsets as possible.
It’s still not clear if there is much market for ultra-thin smartphones, but we should find out soon. The Samsung Galaxy S25 Edge may well be the first out of the gate, with a release rumored for as early as next month.
That would give Samsung a march on its rivals, but if not, it’ll likely arrive in the summer alongside the Galaxy Z Fold 7 and Galaxy Z Flip 7.
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