Apple Watch Ultra 4 Review: Is It the Best Watch for Most Runners? Maybe.

I’ve worn a lot of watches on a lot of long runs. In fact, I’ve tested nearly every running watch from every major brand from Garmin to Samsung to Coros to Suunto. When a new flagship arrives, I’m not looking for what the brand tells me or what it reads like on a spec sheet. I want to see how the dang thing works on my wrist, and what it tells me about my body on a random Monday morning run.After weeks with the Apple Watch Ultra 4, here’s my short answer: this is a vast improvement over the Ultra 3. It isn’t flawless, and I’ll get specific about where it falls short. But for a huge number of runners, it’s the best watch you can buy.What’s Actually Better Than the Ultra 3Generational upgrades are often a polish job. This one isn’t. There are four main improvements that impressed me, and each one changed how I used and viewed the watch day to day:🔋 Battery life and charging speed. Battery life used to suck, and charging was meh at best. That’s no longer the case.🫀 The heart rate sensor. They’ve completely redesigned it from soup to nuts and it’s loads better.⚠️ ECG and hypertension alerts. The health suite feels more mature and more useful.📍 GPS acquisition. The Ultra 3 made you wait, and sometimes the signal never found you. The 4 gets the connection.I’ll take these upgrades in turn, starting with the one that affects you the most as a runner.📍 GPS: No More Standing AroundIf you’ve ever stood on a cold sidewalk waving your wrist at the sky, you know the particular misery of a watch that can’t find satellites. The Ultra 3 was fine on this front, but “fine” included enough hesitation that I’d often start my run before it had locked on.Trevor RaabAWU4 showing on-watch mapping.The Ultra 4 connects fast. I press start, glance down, and it’s ready. Over weeks of runs in open parks, tree-lined streets, and between tall buildings, I didn’t feel delayed or annoyed with the pace of the connections. I want a watch that’s ready when I am, and now this is that watch.📏 Distance Accuracy: Consistently a Little LongNow the first caveat. Once the Ultra 4 locks on, it’s consistent, but it’s consistently off. Across my testing, the watch measured the distance 1 to 1.5 percent long. During a marathon, that’s a few tenths of a mile of ghost distance. On a casual 5K, or a simple run and go, you won’t notice or care. (And hey, more distance on Strava, am I right?) On a tempo run where you’re chasing a specific pace, or when you’re testing your distance mettle, you might.🫀 Heart Rate: Excellent Until You Really RunThe heart rate sensor is where this watch made the biggest leap over the Ultra 3, and also where I have the most nuanced thoughts. I tested it against an external EKG/Holter monitor, which is a much stricter standard than a typical chest strap comparison. (I do not have this specifically for testing. I have this because my heart—though strong AF—sometimes likes to do a little jig or tempo work of its own when I shift my meds.)Trevor RaabThe AWU4 measures heart rate every five seconds.👍 During steady workouts, walking, and easy jogging, the Ultra 4 was excellent. It stayed within two to three beats per minute of the Holter. That’s remarkable for a wrist-based optical sensor, and simply put, throughout the day, I’m trusting it.👎 When I ran harder, the gap widened. The difference between the watch and the Holter grew to between five and seven beats per minute. It’s not catastrophic in terms of variability, and it’s a clear improvement on what I saw from the Ultra 3. But it’s noticeable, and if you train by heart rate zones, it can nudge you into the wrong zone at the margins. But honestly, if you’re doing HR training, you should grab a chest strap. Compared with the Garmin Fenix 9 Pro, which even during hard runs was only off between three and six beats per minute, it was a bit disappointing.The Sampling GapPart of the story is sampling rate. Throughout the day, the Apple Watch records your heart rate roughly every five seconds. The Garmin records it every single second.Over time, that gap matters. When you’re tracking heart rate variability and recovery trends across weeks and months, a denser stream of data gives you a cleaner picture. Five-second sampling means more smoothing, and smoothing can hide the small spikes and dips that tell you how you’re truly recovering or truly struggling.🔋 Battery and Charging: The Fix I Wanted MostBattery anxiety has defined the Apple Watch for years, and the Ultra line was supposed to solve it. The Ultra 3 improved things—a little. The Ultra 4 actually has good battery life, undersold even by Apple’s spec sheet, and just as important, it charges extremely fast. They say you can get two full days in GPS mode. In testing, I ran this thing like I was running for a few days for every minute I wasn’t asleep. In that level of heavy use, I can get three days out of this.Cat BowenThe GPS connects quickly, and the app is laid out beautifully. Pictured on writer’s son’s hand.⚠️ The Health Suite: Where the Ultra 4 Really Pulls AheadECG and Hypertension AlertsThe ECG on the Ultra 4 is noticeably improved over the Ultra 3, and the hypertension alert is seriously nifty. I don’t want to overstate this. These are screening tools, not diagnoses, and they’re not a replacement for a doctor. But for a runner who’s logging the over-90-mile weeks that I do, an early nudge that something’s off in your cardiovascular system is worth a lot.Trevor RaabThe ECG app is easy to use.Menstrual Cycle InsightsAs someone who unfortunately menstruates, I’ve found the cycle insights on this watch are freaking spot on. Whether you’re trying to conceive, trying not to, or trying to figure out how perimenopause is affecting your body, the data and the way it’s presented give a lot of clarity and help, especially when you’re training for a marathon, and the red tent looms.🔍 What’s Missing: The Running Metrics/Mapping GapNow for the part where I give the Garmin its due. The Apple Watch Ultra 4 is not a dedicated running watch, and it doesn’t pretend to be.You won’t find the deeper running dynamics that a Garmin offers: vertical oscillation, stride length, ground-contact balance, and the like. Honestly, and I say this after years of testing, most runners don’t need those metrics and don’t care about them. If you’ve never looked at your vertical oscillation, you won’t miss it. The people who do care already know who they are.Also, offline mapping isn’t straightforward or easy, or even available everywhere. Apple Watches are truly designed to be used either with your phone, or connected to cellular. It does have satellite connectivity for emergencies when you’re out of range, though, and it’s simpler to use than the Garmin satellite comms.The One I Do Miss: Lactate ThresholdThere’s one metric I think a lot of runners would genuinely miss, and that’s lactate threshold. Garmin has it. Apple still does not.Lactate threshold is the pace or heart rate at which your body starts accumulating fatigue faster than it can clear it. Knowing your own lactate threshold is incredibly useful when you're training for distance. It tells you how hard you can push in a tempo run, helps you set meaningful zones, and shows how your fitness is changing over a training block.⌚️ The Smartwatch Side: Apple Does This Better Than AnyoneHere’s where the Ultra 4 runs away from the competition: The smartwatch experience is the foundation.Cat BowenThe watch itself is a bit heavy, but the band is comfortable.Transit pay is seamless. I tap my wrist at a turnstile and walk right through, with no phone, no card fumbling, no button pushing. The same goes for my digital ID card for work.The app ecosystem is unmatched. You simply will not find a better app system on any running watch. Apple knows what it’s doing here. Every workout app I use connected perfectly and worked the way I expected.The phone integration is a delight. I can open my phone, write and send text messages, make calls, and change my music, all from my wrist. When I’m running, I don’t need to dig for my phone or break my stride to skip a track.⚖️ Weight and Design: My Honest ComplaintsTrevor RaabThe watch is heavier on the wrist, but simple to use.It’s heavy. Compared with a dedicated running watch, the Ultra 4 feels like a brick. For short runs it’s fine. On long runs, I lowkey wanted to throw it off my wrist until I got used to it. For ultra-distance running, I noped out and took it off.The shape. This one’s personal, and your thoughts may vary. I’d love to see Apple offer a different form factor. The Ultra’s rugged, squared-off look works for some wrists and not for others, and a slimmer, more rounded option would suit a lot of runners better.💵 Who Should Buy the Apple Watch Ultra 4If I were starting out as a runner, I’d choose this watch without hesitation. The same goes for a runner who leans into an integrated, connected life and wants simplicity and straightforward use. The setup is easy, the interface makes sense, and the health features are impressive and easy to use. You don’t need a manual or a run coach to get a lot out of it.Who should look elsewhere? Ultrarunners, and anyone who trains seriously by heart rate zones at high intensity or relies on advanced running dynamics, will still find the Garmin a better fit. The Fenix 9 Pro’s tighter heart rate accuracy at speed, one-second sampling, and lactate threshold are real advantages for that crowd. Not to mention that extra distance you’re getting in the Garmin which you don’t get from AWU4. (And again, the weight of the watch.)🧑‍⚖️ The VerdictThe Apple Watch Ultra 4 is a vast improvement over the Ultra 3, and not just in one area. Better battery life with very fast charging, a stronger heart rate sensor, improved ECG and hypertension alerts, and faster GPS all come together into a watch that simply makes it a better watch overall.It isn’t perfect. Distance runs consistently 1 to 1.5 percent long. Heart rate accuracy drifts to five to seven beats per minute off during hard running, and the five-second sampling can limit how useful your HRV and recovery data is over time. It’s heavier than I’d like and short on the deeper running metrics, with lactate threshold the one I’d really push Apple to add.Buy Apple Watch Ultra 4 at amazon.com Buy at apple.comCat Bowen, senior editor of commerce; reviews, is a seasoned runner with more than 20 years of distance running experience, including dozens of marathons, half marathons, and even a few ultra marathons. For over a decade, she has tested parenting, fitness, home, and running gear and written in-depth guides to help readers with their next purchase. Holding multiple advanced degrees and currently studying kinesiology, Cat Bowen brings research-backed insight to all of her guides. Passionate about women’s health and neurodivergent inclusion, she advocates for closing research gaps and helping others—especially AudHD people—find joy in running and fitness.