I Tested the Apple Watch Ultra 3’s Battery and This Is How Long It Lasted
After what felt like forever, Apple finally bumped up the Apple Watch’s battery life. The new Apple Watch Ultra 3 jumps from 36 to 42 hours, promising nearly two full days of power, at least on paper. But Apple has a history of being conservative with its battery estimates, so we wanted to find out how long the Ultra 3 actually lasts. Here is our real-world battery test and whether it lives up to the hype.
Apple positions the Ultra 3 as a watch built for endurance athletes, outdoor adventurers, and water sports fans who need a battery that can go the distance. In its official testing, Apple says a full charge in the morning should cover an 18-hour day that includes a 60-minute workout, app usage, notifications, and regular time checks. After that, it should still have enough power to track six hours of sleep and then run for another 18 hours.
What feels a bit strange is that Apple uses six hours of sleep as its benchmark, while most health guidelines recommend seven to nine hours. Still, that was enough to make me curious about how the Ultra 3 would perform in real life. So let’s find out.
Apple Watch Ultra 3 on My Wrist: How Good Is the Battery Life?
I got the Apple Watch Ultra 3 last Friday, but my first proper test started at 00:25 on Saturday. Everything was on: all sensors active, Wi-Fi and Bluetooth connected (no cellular), display brightness set to two-thirds, Always-On Display enabled, and fully paired with a new iPhone 17. I went to bed with Sleep Mode on to track my rest.
Quick disclaimer before we go any further. On a recent bike trip to the Austrian Alps, I injured my Achilles tendon, so I was still in recovery during this test. That meant no running, no strength training, and no long rides. The only workout recorded was a 1 km walk with GPS on for 14 minutes. Even so, the watch logged 15,243 steps on Saturday and 7,683 on Sunday. Most of the time, I used the Ultra 3 to stream music to my AirPods Pro 2, get notifications, and collect health data.
I mention this because this was not a heavy-use scenario. Normally, when reviewing a smartwatch like this, I would include multiple runs, some strength sessions, or a long bike ride. This weekend was nothing like that.
On Sunday at 19:00, the Apple Watch Ultra 3 powered off. The total runtime was 42 hours and 35 minutes, almost exactly what Apple promises, which is impressive on paper. Still, I was expecting a little more, especially after reading many reports of people getting longer runtimes with Always-On Display enabled.
This was not a stress test. There were no hours of continuous GPS tracking or back-to-back workouts, so I would have expected to squeeze out a few extra hours. For what I would call average use, Apple’s estimate seems accurate, but it feels more like a ceiling than a conservative number.
The real evaluation will come once I am back to training and can push the watch under the conditions it was designed for. The Ultra 3 is made for athletes, adventurers, and explorers, and I have not put it through those paces yet.
Apple Watch Ultra 3 Drained: How Fast Does It Charge?
Apple claims that with the new Ultra 3 fast-charging profile, fifteen minutes of charging provides up to 12 hours of normal use, and just 5 minutes is enough for 8 hours of sleep tracking. The company also says you should reach 80 percent in about 45 minutes and a full charge in about 75 minutes.
That is a clear improvement over last year’s Ultra model, which needed about 60 minutes to hit 80 percent and took 99 minutes for a full charge, one of the downsides I noted in our Ultra 2 review.
This year, the Ultra 3 does charge faster, but there is one catch. You need Apple’s 20-watt USB-C power adapter, or a compatible one, to hit those numbers. Otherwise, expect slower results.
Here is why. Even though I have a 20-watt adapter at home, I charged the Ultra 3 with my 30-watt MacBook Air adapter because it was already plugged into the extension cord on my desk. That choice made a big difference.
The new Apple Watch Ultra 3 uses Apple’s updated 20-watt fast-charging profile, which would require roughly 9 volts at 2.2 amps to reach the full twenty watts. The 30-watt MacBook Air adapter does not offer this exact combination, so the watch likely charges at 5 volts by 3 amps (15 watts). As a result, charging took noticeably longer than Apple’s claim of zero to 100 percent in 75 minutes. In my case, it needed 103 minutes to fully charge.
The takeaway is simple. Use Apple’s twenty-watt USB-C adapter or a certified equivalent if you want the advertised fast-charge speeds. Other adapters will work, but you might be waiting longer than expected.
My First Take on the Ultra 3 Runtime
Overall, the Apple Watch Ultra 3 delivers about what Apple promises for battery life, but not more. At $799, I was expecting it to last longer under such low-stress conditions, especially since I did not record any workouts or use many of its premium features during this test. It only charges faster if you use the right adapter, so make sure you have Apple’s 20 W charger or a certified equivalent.
This is just my first look at the Ultra 3, and my full review will be published soon. I would love to know what you want me to test next or what questions you have about this watch.
