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.”