Smartphone Comparison: Samsung Galaxy S21 Ultra 5G vs. Xiaomi Redmi A3
1. Specifications Comparison
Design
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Dimensions | 165.1 x 75.6 x 8.9 mm | 168.3 x 76.3 x 8.3 mm | Redmi A3 is slightly taller and less thick; S21 Ultra 5G might feel more substantial due to its thickness. |
| Weight | 227g | 193g | Redmi A3 is noticeably lighter, making it more comfortable for extended use. |
| Build | Glass front (Gorilla Glass Victus), glass back (Gorilla Glass), aluminum frame | Glass front (Gorilla Glass 3), plastic frame and back | S21 Ultra offers superior screen protection and overall build quality with its materials. |
Display
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Size | 6.8" | 6.71" | Minimal size difference; both offer a large viewing experience. |
| Resolution | 1440 x 3200 | 720 x 1650 | S21 Ultra has a significantly sharper and more detailed display; better for detailed content, photos, and videos. |
| PPI | 515 | 268 | S21 Ultra's higher pixel density results in clearer text and images. |
| Technology | AMOLED | IPS LCD | S21 Ultra offers superior blacks, contrast, color vibrancy and better energy efficiency for dark themes compared to the LCD of Redmi A3. |
| Refresh Rate | 120Hz | 90Hz | S21 Ultra provides a smoother scrolling and animation experience, but the difference to 90 Hz might not be noticeable to all users. |
| Brightness | 1500 nits | 0 nits | S21 Ultra provides much better outdoor visibility under bright sunlight; the Redmi A3 spec is missing so it's likely not very bright. |
Performance
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Chipset | Exynos 2100 (5 nm) | Mediatek Helio G36 (12 nm) | S21 Ultra has a much more powerful processor, leading to significantly better app loading, multitasking, and gaming performance. |
| AnTuTu Score | 749,000 | 127,000 | S21 Ultra is significantly faster, showing 590% better benchmarks performance; suitable for intensive tasks and future-proofing, the Redmi A3 is basic. |
| GPU | Mali-G78 MP14 (International) | PowerVR GE8320 | S21 Ultra’s GPU offers superior graphics performance, crucial for demanding games and video editing. |
Battery
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Capacity | 5000 mAh | 5000 mAh | Similar battery capacity; both should offer comparable battery life under similar usage conditions. |
| Charging | 25W fast charging | 10W fast charging | S21 Ultra charges considerably faster, reducing downtime. |
| Features | Reverse charging, Wireless charging 15W, Reverse wireless charging 9W | None | S21 Ultra offers convenient wireless charging options and can act as a power bank for other devices. The Redmi A3 doesn't offer wireless charging. |
Camera
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Main Camera | 108MP, f/1.8, 1/1.33", 0.8µm | 8MP, f/2.0 | S21 Ultra captures significantly more detailed images, performs better in low light due to larger sensor and aperture. |
| Telephoto 1 | 10.8MP, f/2.4, 1/2.65", 1.22µm | N/A | S21 Ultra offers optical zoom capabilities, allowing for high-quality zoomed-in shots, where Redmi A3 can only do digital zoom. |
| Telephoto 2 | 10.8MP, f/4.9, 1/2.65", 1.22µm | N/A | S21 Ultra provides better zoom capabilities, allowing to zoom further without losing too much quality, not available on Redmi A3. |
| Wide Angle + Macro | 12.2MP, f/2.2, 1/2.55", 1.4µm | N/A | S21 Ultra offers better versatility with ultrawide shots and macro photography, not available on Redmi A3. |
| Selfie Camera | 44MP, f/2.2, 1/2.65", 0.7µm | 5MP, f/2.2 | S21 Ultra captures significantly sharper and more detailed selfies. |
| Video | 8K@24fps, 4K@60fps, 1080p@240fps with HDR, EIS, stereo sound and slow motion up to 960fps | 1080p@30fps | S21 Ultra allows for professional-quality video recording with much higher resolution, frame rates, and advanced features such as HDR and EIS for stabilization, Redmi A3 is very basic. |
| DxOMark Score (Mobile) | 115/121/100 (Main/Photo/Video) | 45/53/37 (Main/Photo/Video) | S21 Ultra significantly outperforms the Redmi A3 in all aspects of mobile photography, including both photo and video quality. |
| DxOMark Score (Selfie) | 135/133/140 (Main/Photo/Video) | N/A | S21 Ultra has a tested high quality front camera; Redmi A3 has no tested score so it's likely not very good. |
| Camera Features | 4K Video, 8K Video, Optical Zoom, OIS, RAW, Night Mode | Digital zoom | S21 Ultra has a plethora of advanced photography features compared to the basic camera of the Redmi A3. |
Software, Connectivity & Storage
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| OS | Android 11 (upgradable to 15) | Android 14 | Redmi A3 comes with a newer version of Android, but S21 Ultra can still be updated to Android 15. |
| WiFi | Wi-Fi 6 (802.11ax) | Wi-Fi 5 (802.11ac) | S21 Ultra supports newer WiFi standards providing faster speeds, lower latency and overall better experience. |
| Bluetooth | 5.2 LE | 5.3 LE | Redmi A3 has a newer Bluetooth version with additional features. S21 Ultra supports a wider array of audio and connectivity profiles. |
| GPS | GPS (L1+L5), Galileo (E1+E5a) | GPS, A-GPS, GLONASS, Beidou | S21 Ultra has better location accuracy, because it supports more satellite systems than Redmi A3. |
| SIM | Dual SIM (Nano) | Dual SIM (Nano) | Both support dual SIM cards. |
| Internal Storage | 128GB/256GB/512GB | 64GB/128GB | S21 Ultra offers significantly more storage space, which is important for storing large files like videos, photos and large apps. |
| RAM | 12GB/16GB | 3GB/4GB/6GB | S21 Ultra has much more RAM, allowing for smoother multitasking and better handling of demanding apps and games. |
| Expandable Storage | No | No | Neither device supports expandable storage. |
Audio & Security
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Audio Quality | Dolby Atmos, Hi-Res Audio, Stereo Speakers | Basic audio | S21 Ultra provides far superior audio quality with immersive spatial audio and better audio fidelity for music listening. |
| Security | basic fingerprint sensor | side-mounted fingerprint sensor | Redmi A3 has a modern fingerprint sensor placed more comfortably on the side of the phone. |
Sensors
| Feature | Samsung Galaxy S21 Ultra 5G | Xiaomi Redmi A3 | Practical Impact |
|---|
| Sensors | Fingerprint, Proximity, Accelerometer, Compass, Gyroscope, Barometer, Hall, Geomagnetic | Accelerometer, Ultrasonic proximity virtual | S21 Ultra has a comprehensive suite of sensors that enable advanced functionalities like AR, VR, and environmental readings. |
2. Key Differences Analysis
Samsung Galaxy S21 Ultra 5G Advantages:
- Superior Display: Significantly higher resolution, pixel density, AMOLED technology, and brightness for a much better viewing experience, especially in bright sunlight.
- Performance Beast: Significantly faster chipset and GPU for demanding tasks, gaming, and future-proofing.
- Professional-Grade Camera: Advanced camera system with significantly better main, ultrawide, telephoto and front cameras, higher quality zoom capabilities, 8K video recording, and a plethora of advanced photo features, like RAW and night mode.
- Faster Charging & Wireless: 25W fast charging, and also includes wireless charging with reverse wireless charging capabilities.
- Enhanced Audio: Includes Dolby Atmos, Hi-Res Audio, Stereo speakers and a noise cancelling microphone.
- More RAM and Storage Options: Offers much higher RAM options and a greater variety of internal storage, allowing to store more photos and apps.
- Better Build Quality: Uses premium materials and has a better screen protection.
Xiaomi Redmi A3 Advantages:
- Lighter Weight: More comfortable for extended use due to its lighter build.
- Newer Android OS: Comes with Android 14 out of the box, but that doesn't mean that it will be updated for much time.
- Side-Mounted Fingerprint Sensor: A more modern fingerprint sensor in a more convenient place.
- Newer Bluetooth: Supports the new Bluetooth version.
- Lower price: This is a much more budget-oriented phone.
Trade-offs
- S21 Ultra: Heavier and older model, can be more expensive.
- Redmi A3: Has a basic camera and screen and slower charging, as well as a weaker processor.
3. User Profiles & Recommendations
Samsung Galaxy S21 Ultra 5G is Ideal For:
- Photography Enthusiasts: Those who prioritize high-quality photos and videos, including advanced zoom capabilities and various shooting modes.
- Power Users: Individuals who need top-tier performance for gaming, multitasking, and demanding applications.
- Media Consumers: Users who enjoy watching high-resolution videos, playing games and need a bright and vibrant screen.
- Professionals: Those who need a reliable device for work, with advanced features, wireless charging and fast charging capabilities.
Specific Use Cases:
- Capturing professional-quality videos for social media.
- Playing graphics-intensive games with smooth performance and a great display.
- Using multiple apps simultaneously without lag.
- Enjoying immersive movies with high resolution and quality audio.
Xiaomi Redmi A3 is Ideal For:
- Budget-Conscious Buyers: Those who need a basic smartphone for essential tasks without a huge cost.
- Casual Users: Individuals who primarily use their phone for calls, messaging, and basic social media.
- First-Time Smartphone Owners: People who are new to smartphones and need something simple to use.
Specific Use Cases:
- Making phone calls and sending texts.
- Browsing social media and watching short videos.
- Listening to music.
- Simple and easy to use as a first smartphone.
Price-to-Value Ratio:
- The S21 Ultra offers much better value for its features and performance, but comes at a higher price. The Redmi A3's value proposition is it's lower cost, but performance is significantly lower.
4. Decision Framework
Key Questions for Buyers:
- How important is camera quality to you? (If photography is a priority, the S21 Ultra is much better.)
- What is your budget? (The Redmi A3 is significantly cheaper, while the S21 Ultra was a flagship at launch and it's still higher in price.)
- How important is performance for your daily use? (If you need a phone for gaming or heavy multitasking, the S21 Ultra is the better choice.)
Scenario-Based Recommendations:
- Scenario 1: Photography Enthusiast:
- Recommendation: Samsung Galaxy S21 Ultra 5G for its advanced camera system and superior image quality.
- Scenario 2: Budget-Conscious Buyer:
- Recommendation: Xiaomi Redmi A3 for its lower price point, and suitable for basic smartphone functionality.
- Scenario 3: Performance-Oriented User:
- Recommendation: Samsung Galaxy S21 Ultra 5G for its powerful processor and great display, providing the best performance.
- Scenario 4: Basic User:
- Recommendation: Xiaomi Redmi A3, if you are ok with the basic functionality, basic camera, poor display and slow performance, it's enough for a normal user.
My Choice
I would choose the Samsung Galaxy S21 Ultra 5G. Although it's an older phone and costs more, the massive improvements in the display, performance, camera, and overall quality make it a much better device, if you can afford it. The higher resolution screen is better for content consumption, the powerful processor will ensure smooth performance for heavy tasks, and the camera has a very good quality that can replace standalone cameras for most use cases. It offers a more premium experience overall, despite it's age. The Redmi A3 is a good phone for basic use, but I personally would go for the S21 Ultra because I value quality more than price.
