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Apple Watch Series 9 review: Why I'm not settling for the less expensive models in 2024

After long-term usage of the Apple Watch Series 9, my hands-on tests found the world's most popular smartwatch is now more accurate at reading your body's health data.
Written by Jason Hiner, Editor in Chief

Apple Watch Series 9

4 / 5
Very good

pros and cons

  • Health sensors are more accurate and more sensitive
  • Screen brightness has doubled for better outside use
  • Improved battery life now easily lasts a full day
  • Double-tap gesture improves one-handed use
  • No blood pressure tracking yet
  • Valuable HRV data is only used by third party apps
  • Sleep tracking is still better with third party apps
  • Accuracy of Series 9 tracking calls older models into question

ZDNET's buying advice 

Inside the Apple Watch Series 9 is the S9 chip which makes the popular smartwatch faster, smarter, and better at reading your body signals -- based on my real-world tests next to the last-generation model (see below for full testing details). That makes the 2023 Apple Watch Series 9 a generational step up. So, if you're in the market for an Apple Watch right now, I'd specifically recommend getting the Series 9 (or the Apple Watch Ultra 2) because the health tracking is such an improvement from previous models.  

Also: The best Apple Watch deals you can buy right now

If you have one of the Apple Watch models from the past few years and your watch is running perfectly fine, you don't need to get the Series 9. There aren't enough upgrade benefits to justify it for most people. However, if you're coming from a Series 6 or earlier and you wear the Apple Watch every day, then you'll likely see a lot of benefits from an upgrade.  

Also: I've tested every Apple Watch model. These are my favorites

If you're coming from a Fitbit or another fitness tracker and are purchasing your first smartwatch -- and nearly two-thirds of Apple Watch buyers are first-timers -- then you'll likely be very happy with how well the Apple Watch Series 9 can track your health, along with its other safety and convenience features. And in 2024 I'd recommend getting the Series 9 over an Apple Watch SE or the Series 8 because it's notably better and more accurate at health tracking, as mentioned above. 

Also: ZDNET's Apple Watch buying guide



LTPO OLED, 396 by 484 pixels, 2000 nits brightness


Apple S9 SiP, 64-bit dual-core, 4-core Neural Engine 




Up to 18-hour lithium-ion battery (36 hours in low power mode) 


GPS, compass, altimeter, high-dynamic-range gyroscope, high-G accelerometer (up to 250G with crash detection), ambient light sensor, blood oxygen sensor, electrical heart sensor, body temperature sensor 


Wi-Fi 4, Bluetooth 5.3, LTE (cellular model only), W3 wireless chip, second generation U1 ultrawideband chip, Emergency SOS satellite connectivity, international emergency calling 

Case materials and colors

 Aluminum: Midnight, Starlight, Silver, Pink, (PRODUCT)RED | Stainless steel: Graphite, Silver, Gold, Space Black (Hermès only) 


IP6X dust-resistant water-resistant to 50 meters 


41mm: Aluminum (32.1g), Stainless steel (42.3g) | 45mm: Aluminum (38.7g), Stainless steel (51.5g) 

$399 to $1,049 

How I tested the Apple Watch Series 9 

I wore the Apple Watch Series 9 on my right wrist for two months and wore last year's Apple Watch Ultra on my left. At the risk of looking like a tech nerd -- and I did have numerous people ask, "Wait, are you wearing two watches?" -- I wanted to not only test the accuracy, battery life, and performance of the latest Apple Watch in the real world but also compare it to last year's technology as a baseline.  

So, I tested both watches with planned and unplanned walks and workouts, including Fitness Plus sessions, tryouts of the new cycling features, and using various kinds of workout equipment in hotels while I was traveling. I also tested sleep tracking, stress tracking (HRV), breathing and mindfulness features, timers, new watch faces, and other built-in apps. I even tested it with some VR workouts by connecting the watch to the Supernatural app and the Meta Quest 3 headset. 

I've been using an Apple Watch every day since the product first launched in the spring of 2015 and I've tested and used the latest model each year since then. So my analysis and buying advice consider the evolution of the Apple Watch over time as well. 

Apple Watch Series 9 hands-on

Apple Watch Series 9 with the the Nike Sport Band (Blue Flame), made partially from recycled older watch bands.

Jason Hiner/ZDNET

What are the best features of the Apple Watch Series 9? 

More accurate and more sensitive health tracking -- The Apple Watch remains a health and safety device above all else, and the new S9 chip inside the Apple Watch Series 9 makes it smarter and more accurate than ever. That was my unequivocal conclusion from two months of wearing the Series 9 on one arm and wearing last year's Apple Watch Ultra on the other arm and comparing the data they captured and the responsiveness of their health sensors. (Remember that the original Apple Watch Ultra from 2022 has the same base technology and sensors as last year's Apple Watch Series 8.)  

My two months of testing showed that the Series 9 was better at several things. It was faster and more accurate at prompting me if I began a walk, for example, but hadn't started a workout to track it on the Apple Watch. The Series 9 almost always triggered a workout prompt earlier than last year's watch, and sometimes triggered one (correctly) when the Apple Watch Ultra never triggered one at all. Another problem that I regularly had with both last year's Series 8 and the original Ultra (and previous Apple Watches) was that they would sometimes lose track of my heart rate in the middle of vigorous workouts like runs, cycling, core exercise, and weight training. When that happened the data for the workout would be thrown off and often become inaccurate. 

As a result, I often had to notch the band tighter during these workouts, which became uncomfortable but did help keep the heart rate at times. Even then, both of last year's devices (and previous Apple Watches before them) would occasionally still lose track of heart rate in the middle of workouts. However, the Series 9 did not have that problem even once during my two months of testing -- even though I never tightened the band during vigorous workouts.  

Just as importantly, I found that when comparing data from workouts, the Series 9 nearly always reported different calorie-burning stats than last year's Apple Watch Ultra, and often had different heart rate numbers as well. As you can see in the chart below, the numbers were off by 10% or more at times -- usually with the Series 9 reporting lower numbers. 

WORKOUTSeries 9 (2023)Ultra (2022)
Indoor Cycling

Total Calories173 CAL309 CAL
Avg. Heart Rate114 BPM116 BPM

Total Calories158 CAL221 CAL
Avg. Heart Rate113 BPM115 BPM
Outdoor Walk

Total Calories241 CAL255 CAL
Avg. Heart Rate101 BPM103 BPM
Core Training

Total Calories23 CAL31 CAL
Avg. Heart Rate102 BPM99 BPM
Strength Training

Total Calories60 CAL75 CAL
Avg. Heart Rate121 BPM119 BPM
Indoor Walk

Total Calories267 CAL227 CAL
Avg. Heart Rate112 BPM113 BPM
Fitness Gaming

Total Calories65 CAL73 CAL
Avg. Heart Rate95 BPM91 BPM
Mindful Cooldown

Total Calories36 CAL28 CAL
Avg. Heart Rate72 BPM78 BPM

When I compared the numbers of both watches with workout equipment like treadmills and spin bikes (including different models in various hotels when traveling, and even when I entered my body stats into the equipment to make it more accurate), it appeared that the Series 9 data is closer to the true numbers. That's made me question whether older Apple Watch models are (inadvertently) inflating calorie-burning data. The bottom line is that my two-month test gave me more trust in the data from the Series 9 -- just as I also had more trust in the Series 9 to not lose my heart rate during workouts and better use its AI to start workouts when I forgot. 

Brighter display for outdoor use -- The Apple Watch Series 9 display has increased its peak brightness from 1000 nits to 2000 nits. This matches the brightness of last year's Apple Watch Ultra (while the Ultra 2 has increased to 3000 nits). This makes the Apple Watch even better to use in full sunlight, especially for outdoor activities like running, walking, hiking, cycling, and sports. At the same time, the display can now also dim down to 1 nit so that the always-on display draws less power. 

Apple Watch Series 9 in full sunlight

Apple Watch Series 9 is now better to use in full sunlight thanks to the upgrade to a display with 2000 nits of peak brightness.

Jason Hiner/ZDNET

True full-day battery life -- The biggest surprise of the Apple Watch Series 9 is the fact that the battery life has improved significantly, even though it has a brighter display and a new, more powerful processor. Apple rated the Series 9 as having the same battery life as the Series 8 -- 18 hours (and 36 hours in low-power mode). 

However, in my real-world tests, I found that the Series 9 is actually quite a bit better. I had days where the watch would have 60% battery left at the end of the day, even while leaving the always-on display turned on and using the watch to track multiple workouts. Last year's Series 8 would typically have 30-40% battery left at the end of a similar day. I chalk up the battery life gains to the efficiency of the new S9 SiP and the ability of the always-on display to now drop down all the way to 1 nit of brightness. 

These battery life gains also make it easier to wear the Apple Watch Series 9 at night for sleep tracking because you can simply put it on the charger for 30-40 minutes at the end of the day and then slip it back on before you go to sleep. 

New double-tap gesture -- The more advanced S9 processor in the Apple Watch Series 9 has also enabled a new double-tap gesture that allows you to more easily operate the watch with one hand. For example, if you have an incoming phone call and your hands are full and you want to answer it with your watch, then you can raise your wrist and double-tap your thumb and forefinger together. 

The gesture is still limited to activating the most prominent action of the app you have open, but it will keep you from having to use your nose to tap the screen when your hands are full -- as many of us have resorted to for years. This is also reminiscent of the new thumb-and-forefinger gesture in the forthcoming Apple Vision Pro headset. So It feels like this is just the beginning, and perhaps even portends a future where the Apple Watch and Vision Pro could work together. 

Double tap gesture on Apple Watch Series 9

Double tap gesture on Apple Watch Series 9.

Jason Hiner/ZDNET

What I'd like to see in the next Apple Watch 

Better stress tracking using HRV -- With the Apple Watch 4, the smartwatch started tracking Heart Rate Variability (HRV), which is a newer health measurement that can be used to track your stress levels. For years, I've been using it to track my stress (I wrote about it on CNET in 2020) and I find it remarkably accurate. However, you have to use third-party apps like HRV Tracker, Stress Monitor, or Welltory to tap into it on Apple Watch. 

Meanwhile, other devices such as Samsung's smartwatches track HRV and directly turn its readings into a stress score. You can trigger an HRV reading automatically on Apple Watch by doing a "Breathe" session in the Mindfulness app, but Apple could do much better by making a separate stress or mental health app on the Apple Watch. This would fit perfectly with the new mood-tracking feature in WatchOS 10

Blood pressure sensor -- High blood pressure (hypertension) is one of the most undiagnosed diseases on the planet and one of the most difficult to manage because it's so difficult to track with a standard blood pressure cuff. And the result is that a lot of people end up with a high risk of heart disease, strokes, and other debilitating ailments. For years, tech companies have been working on ways to use mobile technology to measure blood pressure. That includes putting a finger over the camera on your smartphone paired with an app and software algorithms, as I covered at CES 2019

But an even better option would be to have a smartwatch such as the Apple Watch passively monitoring blood pressure patterns and trends, as well as sending early-warning alerts when there are danger signs. Apple has reportedly been working on bringing blood pressure monitoring to its watch for years. Let's hope the wait is almost over. 

Blood glucose sensor -- Apple has also reportedly been working on integrating a blood glucose sensor, which is even more difficult than integrating a blood pressure sensor since today's blood glucose measurements involve drawing blood. First and foremost, this would help people with diabetes (over half a million globally) to manage this complex condition without having to prick their finger for blood so many times a day. 

Even if you don't have diabetes, monitoring blood glucose can also have benefits for managing your health in other ways by offering insights into your diet/nutrition, energy levels, and when to schedule medicines, meals, and workouts. That said, we could still be years away from Apple and other companies bringing non-invasive blood glucose tracking to wearables such as the Apple Watch -- but it will be a big breakthrough when it happens.

Apple Watch Series 9 with new Snoopy watch face and Nomad band

Apple Watch Series 9 with the new Snoopy watch face and Nomad's 2023 Limited Edition Sport Band.

Jason Hiner/ZDNET

Final thought 

Because of the generational technology leap with the Series 9, I'd recommend getting this model rather than the Apple Watch SE or the previous Series 8 or Series 7 models that you can still buy -- since the Series 9 technology will remain current for longer and is likely to benefit from future software upgrades for longer. The more sensitive and accurate health tracking sensors make previous Apple Watches feel outdated by comparison. 

Alternatives to consider 

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