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Apple Watch Ultra battery could be almost twice as big as Apple Watch 8

Apple Watch Ultra
(Image credit: Future)

If you want the ultimate Apple Watch experience, it’s looking like you should invest in the Apple Watch Ultra. Complete with a new, and durable, design, it has plenty of things you won’t see on the Apple Watch 8 — including a multi-day battery life. And according to a new report, that last feature is all down to a super-sized battery.

According to MySmartPrice (opens in new tab), new regulatory filings have revealed just how big the Apple Watch Ultra’s battery really is — and that's apparently a whopping 542 mAh. If true, that makes it 76% bigger than the 45mm Apple Watch 8’s 308 mAh battery, and 92% bigger than the 41mm model’s 282 mAh.

Apple claims that the Apple Watch Ultra can last 36 hours on a single charge, which is double the time of a standard Apple Watch — Apple Watch 8 included. We haven’t had a chance to put that figure to the test just yet, but it makes sense that double the battery life would require a battery that’s almost twice as big.

Of course, Apple does caveat the figure slightly by stating that the Ultra’s battery life is “up to” 36 hours, so in the real world that number might vary. According to Apple (opens in new tab), this figure came from testing in which the Ultra was connected to LTE for eight hours and an iPhone Bluetooth connection for a further 28. 

Meanwhile, the Apple Watch 8’s 18-hour battery life involves four hours of LTE and 14 hours on Bluetooth. Keeping LTE on all the time means you’re getting significantly less time out of your battery — just 18 hours on the Ultra, according to Apple. 

So that’s all worth bearing in mind when you pick up a new watch for yourself. But don’t forget about the new Low Power mode, which can help preserve your battery for even longer than the official estimate; 60 hours, apparently. 

Of course, battery life isn’t the only difference between the two new Apple Watches. The Ultra also comes with water resistance up to 100 meters (up from 50), an 86 decibel emergency siren, L1 and L5 GPS, as well as a 2,000 nit always-on display — compared to the Apple Watch 8’s 1,000 nits.

The Apple Watch Ultra also offers a 49mm display with a chassis made from titanium, which is much stronger than aluminum or stainless steel. Then again, it also costs $799; that’s quite the increase from the Apple Watch 8, which starts at $399 or $499 with LTE.

Apple Watch 8 preorders are live now, ahead of release later this month. The Apple Watch 8 lands on September 16, alongside the iPhone 14, iPhone 14 Pro and iPhone 14 Pro Max. The Apple Watch Ultra lands a week later, on September 23.

Tom Pritchard
Automotive Editor

Tom is the Tom's Guide's Automotive Editor, which means he can usually be found knee deep in stats the latest and best electric cars, or checking out some sort of driving gadget. It's long way from his days as editor of Gizmodo UK, when pretty much everything was on the table. He’s usually found trying to squeeze another giant Lego set onto the shelf, draining very large cups of coffee, or complaining that Ikea won’t let him buy the stuff he really needs online.