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The OnePlus 9 and the OnePlus 9 Pro are finally here bringing the ultra-fast flagship performance, design, and this time around, improved camera systems. While the OnePlus 9 Pro is set to aim high against the Ultras and the Pro Maxes out there, the vanilla OnePlus 9 is the smaller device, but nonetheless ‒ a flagship model with a mighty camera. On the other hand, we have the Galaxy S21 ‒ the smallest of Samsung’s S flagships this year, but still capable and mighty-fast, which is a direct OnePlus 9 competitor.
Here, we compare these two phones in several key categories: design, display, performance, cameras, and battery life. If you’re looking into upgrading this year to either the OnePlus 9 or the Galaxy S21, let’s explore how they compare with each other.
OnePlus 9 vs Samsung Galaxy S21: design and colors
Samsung went in a very interesting design direction with the launch of the Galaxy S21 series, which has that unique approach to the camera bump on the back, and on top of that, the S21 comes in four fresh and interesting colors: Phantom Violet, Phantom Pink, Phantom White, and Phantom Grey. On the front of the phone, we see a beautiful 6.2-inch AMOLED display with a centered punch-hole for the selfie camera and razor-thin bezels.
On the other hand, OnePlus is not changing the design of the OnePlus 9 from the OnePlus 8T too much. The phone resembles the OnePlus 8T quite a lot, at least in the front, with its left-hand-side punch-hole camera and its flat screen. On the back, it has a slight curve for a comfortable hold. As for the colors, the OnePlus 9 comes in three gorgeous colors: Astral Black, Arctic Sky (not available in the States as of now), and Winter Mist.
The OnePlus 9 feels well-balanced and comfortable to hold, and so does the Galaxy S21. One difference to mention here is the S21 has a plastic back, while the OnePlus 9 has a glass back.
OnePlus 9 vs Samsung Galaxy S21: display
120Hz display refresh rate on both
6.55-inch vs 6.2-inch display
The Galaxy S21’s 6.2-inch display rocks an FHD+ resolution, meaning 1080 x 2400, and the same resolution graces the OnePlus 9, which has a slightly bigger display at 6.55 inches. The difference in both displays means that, at least on paper, the Galaxy should offer a crisper image with a higher pixel density than the OnePlus 9. However, we are talking here about a few pixels, so that difference is hardly visible with the naked eye.
The OnePlus 9’s display does differ as much from the OnePlus 8T’s, which was graded an A+ by DisplayMate.
The CIE 1931 xy color gamut chart represents the set(area)of colors that a display can reproduce,with the sRGB colorspace(the highlighted triangle)serving as reference.The chart also provides a visual representation of a display's color accuracy. The small squares across the boundaries of the triangle are the reference points for the various colors, while the small dots are the actual measurements. Ideally, each dot should be positioned on top of its respective square. The 'x:CIE31' and 'y:CIE31' values in the table below the chart indicate the position of each measurement on the chart. 'Y' shows the luminance (in nits) of each measured color, while 'Target Y' is the desired luminance level for that color. Finally, 'ΔE 2000' is the Delta E value of the measured color. Delta E values of below 2 are ideal.
The Color accuracy chart gives an idea of how close a display's measured colors are to their referential values. The first line holds the measured (actual) colors, while the second line holds the reference (target) colors. The closer the actual colors are to the target ones, the better.
The Grayscale accuracy chart shows whether a display has a correct white balance(balance between red,green and blue)across different levels of grey(from dark to bright).The closer the Actual colors are to the Target ones,the better.
Another key feature, present on flagship Android phones, is the 120Hz display refresh rate. The Galaxy S21 has an adaptive 120Hz refresh rate that can go down to 48Hz, depending on the content you are visualizing. The OnePlus 9 also sports a buttery-smooth 120Hz display refresh rate. You can choose between 60Hz and 120Hz for the display, and it does not have the LTPO tech we have with the OnePlus 9 Pro. However, the phone smartly lowers the refresh rate to 60Hz when you’re watching YouTube videos to conserve battery life, given the fact that YouTube videos cannot go as high as 120Hz for refresh rate.
OnePlus 9 vs Samsung Galaxy S21: hardware and performance
The Galaxy S21, as expected, comes equipped with the industry’s greatest, Snapdragon 888 flagship processor (at least in the States), while in Europe it features Samsung’s own Exynos 2100 chip. The OnePlus 9 is also powered by the mighty Snapdragon 888, so in terms of performance, both phones perform on that fast and snappy flagship level we would expect. As always, the OnePlus 9 delivers a smooth performance, so there are no surprises here. The phone is also great with gesture navigation.
An aspect that’s important to note here is that OnePlus phones are known to remain fast even after years of usage, while other Android phones can get relatively slower, so that’s something worth mentioning when talking about the OnePlus 9 as well.
In terms of operating systems, the OnePlus 9 comes with Oxygen OS 11 on top of Android 11, which is very smooth and now it finally has an auto dark mode. The smooth OS makes using the OnePlus 9 a pleasure and its gesture navigation doesn’t lag as it sometimes does on Galaxy phones. Additionally, it brings customization options and a new Turbo Boost 3.0 memory optimization, helping with apps opened in the background. Gamers can enjoy Pro Gaming Mode that optimizes the CPU and GPU of the phone for gaming and blocks distractions such as notifications.
For the Galaxy S21, we get all the perks of One UI 3.1 and Android 11, which brings revamped notifications and loads of customization options hidden in the wonderful world of Advanced Settings. You get enhanced lock-screen widgets and digital wellbeing applications to help you monitor your smartphone use. Overall, both One UI and OxygenOS are smooth and fast, as is expected from flagship phones.
OnePlus 9 vs Samsung Galaxy S21: cameras
Triple cameras on both
48MP main vs 12MP main
50MP ultrawide vs 64MP zoom
The camera department is an aspect where OnePlus hasn’t been investing as much, but this year, things have finally changed. The company is partnering with Hasselblad to offer several improvements in the camera department, where usually OnePlus phones struggle to be on par with the best in mobile photography. Let’s explore how OnePlus did this time and how it fares against the Galaxy.
Starting with specs, the Galaxy S21 comes equipped with a triple camera system, featuring a 12MP main sensor, a 64MP zoom camera, and a 12MP ultra-wide camera. The photo quality the phone produces is top-notch: the images have a fantastic dynamic range, true-to-life colors, and sharp details. Overall, photos from the Galaxy S21 turn out great, as you can see on the samples down below.
As for OnePlus, the partnership with Hasselblad is the focus of this year’s flagship models. The OnePlus 9 has Natural Color Calibration with Hasselblad, aimed to deliver more realistic and colorful photographs. The phone is equipped with a 48MP main sensor, a 50MP ultra-wide camera with a large Sony IMX766 sensor (which is the same sensor as in the Pro), and a third sensor that is a monochrome camera.
What really impressed us when talking about the OnePlus 9 camera is the improved macro mode, which gives pretty stunning results. Something we noticed about the OnePlus 9’s camera is that the colors in the photos are a bit more muted than those of the Galaxy, where colors pop and are overall pleasant to look at. A cool addition to the OnePlus 9’s camera arsenal is the improved Nightscape mode, which makes night shots brighter and more detailed.
Here you can see how the Galaxy's photo is a big more colorful, while the one from OnePlus 9 is somewhat more muted. That being said, we can see both phones successfully portray details and dynamic range.
Here, take a look at some night samples on both phones, using portrait mode:
In terms of video, the Galaxy is capable of recording 8K video at 24 frames per second, which is a look towards the future for many people. On the other hand, the OnePlus 9 clearly shows improvements over last year in the video department, although the phone crops in the video too much with the ultra-wide, which limits the range the ultra-wide camera can shoot.
Here we see the OnePlus 9 earn a point, especially with charging. The OnePlus 9 rocks a 4,500mAh battery cell, while the Galaxy S21 comes with a 4,000mAh battery, definitely not small either. In our tests, the Galaxy offers a dependable battery life, but it did score less in our extensive battery tests than the OnePlus 9, although the difference in real life is hardly noticeable between the two.
A strong point the OnePlus 9 earns here is charging: the Warp Charge OnePlus brags with is indeed a great addition to a smartphone in our busy everyday life. The company claims the phone can be charged from 1% to 100% in just 29 minutes, while for 15 minutes, it should get some juice to last you a day.
OnePlus 9 vs Samsung Galaxy S21: price and availability
OnePlus 9 starts at $729 for base storage
Galaxy S21 starts at $799 base storage
The OnePlus 9 has now been announced and pre-orders start on March 26, with the official release date of April 2. This is slightly more expensive than what the OnePlus 8 retailed at; however, the price difference isn’t that big for what the phone has to offer. The Galaxy S21 is slightly more expensive than the OnePlus 9 and is already available in the US and globally.
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Izzy, a tech enthusiast and a key part of the PhoneArena team, specializes in delivering the latest mobile tech news and finding the best tech deals. Her interests extend to cybersecurity, phone design innovations, and camera capabilities. Outside her professional life, Izzy, a literature master's degree holder, enjoys reading, painting, and learning languages. She's also a personal growth advocate, believing in the power of experience and gratitude. Whether it's walking her Chihuahua or singing her heart out, Izzy embraces life with passion and curiosity.
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