Galaxy S21 Ultra 5G vs Realme C21
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Galaxy S21 Ultra 5G
Starting at
£268.86£1,316.00 new
Realme C21
Starting at
£198.00What's the difference between the Galaxy S21 Ultra 5G and Realme C21?
Galaxy S21 Ultra 5G vs Realme C21 comes down to the chipset, RAM and screen size. Refurbished, the Realme C21 starts at £198, £70.86 less than the Galaxy S21 Ultra 5G.
Refurbished from
Chipset
RAM
Screen size
Screen type
Main camera
- Chipset: Exynos 2100 (5 nm), Qualcomm SM8350 Snapdragon 888 5G (5 nm) on the Galaxy S21 Ultra 5G, Mediatek MT6765G Helio G35 on the Realme C21.
- The Galaxy S21 Ultra 5G has more RAM: 12 GB vs 4 GB.
- Screen size: 6.8 inch on the Galaxy S21 Ultra 5G, 6,5 inch on the Realme C21.
Galaxy S21 Ultra 5G vs Realme C21 specs
The Galaxy S21 Ultra 5G and Realme C21 are both 2021 Android smartphones that suit different needs. The Galaxy S21 Ultra 5G offers a high-end experience with a large, high-resolution AMOLED screen, powerful chipset options, and a very high RAM capacity, making it fit for demanding apps and multitasking. It also supports 5G networks and has a versatile camera setup with very high megapixel counts. The Realme C21 suits everyday use with a simpler processor, less RAM, and a lower resolution IPS LCD screen. It supports 4G networks and includes a microSDXC slot for extra storage, which is useful if you want to expand beyond its 64GB capacity.
Galaxy S21 Ultra 5G vs Realme C21 price
Colour
Storage
Galaxy S21 Ultra 5G vs Realme C21 battery life and software updates
Durability covers battery size, software support, and core design features that affect daily reliability and lifespan. Both devices share some traits but differ in software updates and SIM options.
Battery Capacity
Both the Galaxy S21 Ultra 5G and Realme C21 have a 5000 mAh battery. This capacity offers a solid amount of power for daily use, helping the devices last through a full day of typical activities like browsing, calls, and media playback.
SIM Card Options
The Galaxy S21 Ultra 5G uses a combination of a physical SIM and an eSIM, offering flexibility if you want to use two numbers without needing two physical cards. The Realme C21 supports dual physical SIM cards, giving you two separate slots for SIMs.
Battery
Foldable
Ip rating
Software updates
Wireless charging
Year of release
Galaxy S21 Ultra 5G vs Realme C21 performance
Performance depends on the chipset, RAM, and storage capacity. These influence how smoothly apps run, multitasking ability, and how much data you can keep on the device.
Chipset Power
The Galaxy S21 Ultra 5G features high-end chipsets: the Exynos 2100 or the Qualcomm Snapdragon 888 5G, both built on a 5 nm process. These chipsets are designed to handle demanding tasks and high-performance apps efficiently. The Realme C21 uses the Mediatek Helio G35, which targets everyday tasks and lighter app use.
RAM Capacity
With 12 GB of RAM, the Galaxy S21 Ultra 5G can keep many apps open and running smoothly, supporting intensive multitasking and gaming. The Realme C21 comes with 4 GB of RAM, which is suitable for basic multitasking and general app use.
Storage Options
The Galaxy S21 Ultra 5G is available with 128GB, 256GB, or 512GB of internal storage, providing ample space for apps, photos, and media. The Realme C21 offers 64GB of storage, which is enough for essential use and can be expanded using a microSDXC card.
Chipset
RAM
Galaxy S21 Ultra 5G vs Realme C21 screen
Screen quality affects how you view content, from resolution and size to display technology. These factors influence sharpness, colour richness, and screen size comfort.
Resolution and Detail
The Galaxy S21 Ultra 5G has a 1440 x 3200 resolution, delivering very sharp and detailed images, ideal for watching high-definition videos and viewing detailed photos. The Realme C21 uses a 720 x 1600 resolution, suitable for everyday viewing but with less sharpness compared to higher resolutions.
Screen Size
The Galaxy S21 Ultra 5G features a 6.8 inch screen, providing a spacious display for media, gaming, and productivity. The Realme C21 has a slightly smaller 6.5 inch screen, which remains comfortable for most daily tasks and easier to handle with one hand.
Display Technology
The Galaxy S21 Ultra 5G uses Dynamic AMOLED 2X technology, known for vibrant colours, deep blacks, and high brightness. The Realme C21 has an IPS LCD screen that offers good colour accuracy and viewing angles, suited for everyday use.
Refresh rate
Resolution
Screen size
Screen type
Galaxy S21 Ultra 5G vs Realme C21 camera
Audiovisual features focus on camera quality, important for photography and video calls. Higher megapixel counts can capture more detail in images.
Main Camera Resolution
The Galaxy S21 Ultra 5G's main camera has 108 megapixels, allowing for very detailed photos and greater flexibility in cropping or zooming. The Realme C21's main camera has 13 megapixels, which supports clear shots for everyday photography.
Front Camera Resolution
The Galaxy S21 Ultra 5G includes a 40 megapixel front camera, suited for high-resolution selfies and video calls with fine detail. The Realme C21 has a 5 megapixel front camera, which works well for standard video calls and simple selfies.
Camera type
Front camera
Main camera
Galaxy S21 Ultra 5G vs Realme C21 size and design
Other differences include network compatibility, physical size, weight, and additional features like expandable storage and SIM card setup.
Network Support
The Galaxy S21 Ultra 5G supports 5G mobile networks, which is beneficial if you want faster data speeds where 5G coverage is available. The Realme C21 supports 4G networks, providing reliable connectivity for everyday use.
Expandable Storage
The Realme C21 includes a microSDXC card slot, allowing you to add extra storage beyond the internal 64GB. The Galaxy S21 Ultra 5G does not have a microSD card slot, so storage depends on the internal capacity you choose.
Device Dimensions and Weight
Both phones are very similar in height and depth, with the Galaxy S21 Ultra 5G at 165.1 mm tall and 8.9 mm thick, and the Realme C21 at 165.2 mm tall and 8.9 mm thick. The Galaxy S21 Ultra 5G weighs 227 g, making it heavier than the Realme C21, which weighs 190 g. The width is 75.6 mm for the Galaxy and 76.4 mm for the Realme.
Carrier compatibility
Connector
Depth
Height
Mobile network
Release date
SD card slot
SIM card
Weight
Width
Galaxy S21 Ultra 5G or Realme C21: which should you buy?
Buy the Galaxy S21 Ultra 5G if
- you want more RAM (12 GB vs 4 GB)
- you want an OLED screen
- you want a higher-resolution main camera (108 megapixels vs 13 megapixels)
Buy the Realme C21 if
- you want to spend less: it starts at £198, £70.86 less than the Galaxy S21 Ultra 5G
- you want a lighter build (190 g vs 227 g)
- you want a memory card slot
Galaxy S21 Ultra 5G vs Realme C21 FAQs
Galaxy S21 Ultra 5G vs Realme C21 comes down to the chipset, RAM and screen size. Chipset: Exynos 2100 (5 nm), Qualcomm SM8350 Snapdragon 888 5G (5 nm) on the Galaxy S21 Ultra 5G, Mediatek MT6765G Helio G35 on the Realme C21. The Galaxy S21 Ultra 5G has more RAM: 12 GB vs 4 GB.
The Realme C21 is cheaper refurbished, from £198 compared with £268.86 for the Galaxy S21 Ultra 5G.
Both have the same battery: 5000 mAh.
The Galaxy S21 Ultra 5G has a higher-resolution main camera: 108 megapixels vs 13 megapixels.
Updates for the Galaxy S21 Ultra 5G ended in Feb 2026. We don't have published update dates for the Realme C21.
Refurbished, the Galaxy S21 Ultra 5G comes in 128GB, 256GB and 512GB, and the Realme C21 in 64GB.
