# Apple Watch Ultra 4 review: Stronger battery, better tracking > The adventure smartwatch gets a major sensor upgrade and lasts longer than ever, but some features aren't ready yet. - Title: Apple Watch Ultra 4 review: Stronger battery, better tracking - Summary: The adventure smartwatch gets a major sensor upgrade and lasts longer than ever, but some features aren't ready yet. The Ultra 4's new Health Sensing System… - Keywords: apple watch ultra 4, apple, smartwatch, wearables, heart rate tracking, health sensing system, battery life, apple watch series 12, garmin, whoop, oura, fitness tracking - Source: Men's Health — https://menshealth.com/technology-gear/a73759657/apple-watch-ultra-4-review - Author: Brett Williams, NASM - Published: 2026-09-17T12:00:00+00:00 - Read time: 3 min - Topics: apple watch ultra 4, apple, smartwatch, wearables, heart rate tracking, health sensing system, battery life, apple watch series 12, garmin, whoop, oura, fitness tracking ## Ultra 4 checks your heart constantly The adventure smartwatch now has a new Health Sensing System that dramatically improves heart rate tracking capability. ## Ultra and Series 12 converge The Ultra 4 and Series 12 share the same sensors and health features. Main differences are form factor, battery, and backcountry capabilities. ## Why the reviewer picks Ultra The larger device offers more heft and extra battery power, perfect for packing in multiple workouts each week. > I love the heft of the larger device, and given all the workouts I tend to pack into my week, I treasure the extra battery power. ## Redesigned sensor on your wrist The rear sensor has more skin contact area, a circular optical array, and larger LEDs. Same 49mm size, better performance. ## Heart rate every 5 seconds The Watch now continuously updates heart rate data every five seconds, versus background readings every five minutes before. ## Still behind some competitors Garmin reads multiple times per second and Whoop claims readings every second. Apple's upgrade is new for them, not the industry. ## Apple claims most accurate tracking A 1,000-plus subject study tested against Garmin, Whoop, Google, Samsung, and Oura using a Polar chest strap as reference. ## Real world accuracy check Wearing Ultra 4 and Whoop on opposite wrists, the heart rate readings were consistently two to five BPM apart. ## Trends matter more than precision Wearing your device consistently lets you spot patterns over time to flag for your doctor, which is more useful than exact readings. > As long as I wear my device consistently, the trends I can spot over time (and potentially flag for my doctor) are what will be truly useful for my health. ## Two different HRV scores Recovery HRV measures every five minutes at rest for daily data. Overall HRV tracks broad patterns for cardiovascular health. ## HRV compared to competitors Apple Watch showed 95ms, Whoop 106ms, and Oura 107ms. Close, but a nearly 10ms difference raises questions worth tracking over time. ## New Readiness score arrives The feature rates you 1 to 10 based on Fitness, Vitals, and Sleep Score to show how prepared your body is for the day. ## More health features coming later A longevity tab and Health Age measure similar to Whoop and Oura will arrive at some point later this year. ## S11 chip powers new features The processor enables faster performance, a pedometer complication, enhanced Siri, and new Audio Intelligence functions. ## Audio Intelligence tools debut Sound Recognition alerts you to common sounds. Music Recognition puts Shazam in Smart Stack for quick song identification with Double Tap. ## Conversation features raise privacy questions Live Rewind transcribes 15 seconds of conversation. Siri Recap summarizes your day's talks. Both require opt-in and come later this year. ## Battery lasts up to 50 hours Apple claims 50 hours everyday use, 84 in low power. Workout tracking goes 18 hours continuous, or up to 45 in max extended mode. ## Fast charging saves the day Fifteen minutes of charging provides the equivalent of 18 hours of use. From 10 percent to three-quarters charged while getting ready for bed. ## Still trails adventure watch rivals Competitors last weeks between charges, not days. But the Ultra 4 handled an eight-hour trail race with plenty of battery left. ## Who should buy the Ultra 4 Get it if you want long battery life and don't mind the 49mm size or $799 price. Series 12 at $399 offers similar features in smaller form. > Over the last few years, the Ultra is the smartwatch I continue to find myself going back to, and I don't expect that to change anytime soon. It just works. ## Key takeaway The Ultra 4's new Health Sensing System tracks heart rate every 5 seconds instead of every 5 minutes, making it Apple's most accurate wearable yet.