This OnePlus 9 and 9 Pro battery life test reveals if they can match Samsung's Galaxy S21


Our OnePlus 9 and 9 Pro battery tests are ready and if you ever wondered whether the 4,500mAh battery inside both phones can match the competition, well... it turns it is a good balance point.

Here is what we mean: the battery on the OnePlus 9 and OnePlus 9 Pro might be a bit smaller than on the Galaxy S21 series, but it shows surprising resilience in tasks like playing back videos or gaming, but for lighter use like just browsing the web, the Galaxy S21 series still scored way higher.

First, though, let's clarify that with about the same screen size, default 1080p resolution, and same sized 4,500mAh battery cell means that the battery life on the OnePlus 9 is practically identical to the one on the Pro model. The big advantage of the Pro is having an adaptive screen that switches on demand: from 1Hz for static content like images to 120Hz for super smooth scrolling, and that saves battery. The effect, however, is quite subtle in our testing, so let's take a look.



Test #1: Web browsing at 120Hz and 60Hz


hours Higher is better
OnePlus 9 Pro
11h 45 min
OnePlus 9
11h 45 min
OnePlus 8 Pro
10h 54 min
OnePlus 8T
10h 54 min
Samsung Galaxy S21 Ultra
16h 7 min
Samsung Galaxy S21+
12h 11 min
Samsung Galaxy S21
9h 6 min
Apple iPhone 12 Pro Max
14h 6 min
Apple iPhone 12 Pro
12h 35 min
Apple iPhone 12 mini
10h 56 min
Google Pixel 5
12h 40 min

On our web browsing casual use test, the OnePlus 9 and 9 Pro scored identical results, meaning that we did not get to see any huge battery life benefit from the dynamic refresh rate on the Pro. Compared to other phones, the OnePlus 9 series are just average on this test, and we found that to be also true in real life use where the phones would require a top up a bit earlier than other beefier flagships like the Galaxy S21 Ultra or the iPhone 12 Pro Max.

Test #2: YouTube video streaming


hours Higher is better
OnePlus 9 Pro
9h 16 min
OnePlus 9
9h 16 min
OnePlus 8 Pro
9h 15 min
OnePlus 8T
8h 48 min
Samsung Galaxy S21 Ultra
8h 52 min
Samsung Galaxy S21+
8h 27 min
Samsung Galaxy S21
7h 36 min
Apple iPhone 12 Pro Max
8h 37 min
Apple iPhone 12 Pro
6h 48 min
Apple iPhone 12 mini
5h 10 min
Google Pixel 5
8h 49 min

We also run a YouTube video streaming test and if - like me - you like to watch a ton of video on your phone, then the results here should be of value.

Unlike the browsing test, the OnePlus 9 series actually excel for watching videos not just because of the beautiful displays, but because battery life is so good in this use case. In fact, the 9 series were able to outlast the S21 Ultra and the iPhone 12 Pro Max here.

One thing we did notice is that if you use your new OnePlus phone at 120 Hertz, it will automatically drop to 60Hz while watching videos on YouTube.

Test #3: 3D gaming


hours Higher is better
OnePlus 9 Pro
9h 6 min
OnePlus 9
9h 6 min
OnePlus 8 Pro
10h 33 min
Samsung Galaxy S21 Ultra
8h 40 min
Samsung Galaxy S21+
8h 36 min
Samsung Galaxy S21
7h 9 min
Apple iPhone 12 Pro Max
8h 1 min
Apple iPhone 12 Pro
6h 46 min
Apple iPhone 12 mini
5h 10 min
Google Pixel 5
6h 51 min

Finally, OnePlus has done some clever cooling engineering to keep the phone at a reasonable temperature while playing games. And it also scores great on our 3D gaming test which stresses the GPU, while the other two tests put the strain on the CPU.

With a score of more than 9 hours, the OnePlus 9 series can last more than many other phones for your gaming sessions, be it PubG or Call of Duty Mobile.

Conclusion


At the end of the day, the OnePlus 9 and 9 Pro with their 4,500mAh cells are a mixed bag when it comes battery life. They do drain quicker than other phones in casual use, but thanks to clever cooling they last more than you'd expect in YouTube video streaming and 3D gaming.

Related phones

9 Pro
  • Display 6.7 inches 3216 x 1440 pixels
  • Camera 48 MP (Quad camera) 16 MP front
  • Hardware Qualcomm Snapdragon 888 8GB RAM
  • Storage 128GB, not expandable
  • Battery 4500 mAh
  • OS Android 11 OxygenOS UI
9
  • Display 6.5 inches 2400 x 1080 pixels
  • Camera 48 MP (Triple camera) 16 MP front
  • Hardware Qualcomm Snapdragon 888 8GB RAM
  • Storage 128GB, not expandable
  • Battery 4500 mAh
  • OS Android 11 OxygenOS UI

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