Samsung Galaxy S21 - Complete Review
Samsung Galaxy S21 - Complete Review & Comprehensive Buying Guide
The Samsung Galaxy S21 marked a pivotal shift in Samsung's flagship strategy. By lowering the entry price and making calculated trade-offs in materials and resolution, Samsung aimed to make the "S" series more accessible without sacrificing raw performance. Years after its release, the S21 remains a compelling option in the secondary market and for users holding onto compact powerhouses.
In this technical analysis, we move beyond the marketing hype to examine the long-term viability of the Galaxy S21. We will analyze its thermal performance, battery degradation over time, and whether the controversial "Glasstic" back has stood the test of time. This guide is designed for tech enthusiasts and potential buyers looking for a high-value device in the current smartphone landscape.
Expert Opinion Snapshot: The Compact Powerhouse
Before diving into the deep technical specifications, here is a summary of our findings after extensive testing. The S21 fits a specific user profile: those who demand flagship processing power in a form factor that is easily usable with one hand.
The Pros (Why Buy?): - Ergonomic Excellence: One of the most comfortable phones to hold due to its dimensions and weight balance. - Display Quality: Despite the drop to 1080p, the Dynamic AMOLED 2X panel offers class-leading brightness and color accuracy. - Software Support: Samsung's commitment to 4 years of OS updates keeps this device relevant and secure. - Ultrasonic Fingerprint Gen 2: Significantly faster and more reliable than the S20 series.
The Cons (The Trade-offs): - No MicroSD Slot: A major departure for Samsung fans; you are stuck with the internal storage you buy. - Box Contents: No charger or earphones included in the box. - Plastic Back: While durable, it lacks the premium cold touch of glass found on the S21+ and Ultra.
Full Technical Specifications
| Feature | Specification Details |
| Display Panel | 6.2-inch Dynamic AMOLED 2X, 120Hz, HDR10+, 1300 nits (peak) |
| Resolution | 1080 x 2400 pixels (20:9 ratio), ~421 ppi density |
| Processor (SoC) | Qualcomm Snapdragon 888 (USA/China) OR Exynos 2100 (Global) |
| RAM & Storage | 8GB RAM (LPDDR5) with 128GB or 256GB (UFS 3.1) |
| Build Materials | Gorilla Glass Victus (Front), Polycarbonate (Back), Aluminum Frame |
| Water Resistance | IP68 Dust/Water Resistant (up to 1.5m for 30 mins) |
Ergonomics, Build & Materials
The most discussed aspect of the S21 is its "Glasstic" rear panel. Technically reinforced polycarbonate, this material choice was controversial for a flagship. However, in practical usage, it offers distinct advantages over glass. It is less prone to shattering upon impact, significantly lighter, and resists fingerprints better than glossy glass backs.
Samsung integrated the camera bump directly into the aluminum frame, a design language known as the "Contour Cut." This not only looks distinctive but also protects the camera module edges from direct impact. The device feels dense and premium, despite the plastic back, thanks to the high-quality metal rails and tight manufacturing tolerances.
Display Capabilities: Is 1080p Enough?
The downgrade from the S20's QHD+ resolution to FHD+ (1080p) on the S21 caused concern among purists. However, at a 6.2-inch screen size, the pixel density remains over 400 ppi, making individual pixels indistinguishable to the naked eye.
Expert Insight: The real star here is the Adaptive Refresh Rate. While it doesn't drop to 1Hz like the Ultra model (it ranges between 48Hz and 120Hz), the implementation is smooth. The panel is exceptionally bright, hitting 1300 nits peak, which ensures perfect legibility even under direct sunlight. HDR10+ support makes content consumption immersive with deep blacks and vibrant contrast.
Performance, Thermals & Gaming
Depending on your region, the S21 houses either the Snapdragon 888 or the Exynos 2100. The Exynos 2100 was a massive improvement over its predecessor (Exynos 990), eliminating the severe battery drain and idle heat issues. Both chips use a 5nm process, offering flagship-level speed for app opening, multitasking, and image processing.
Thermal Throttling: Due to the compact chassis, heat dissipation is physically limited. During extended gaming sessions (e.g., PUBG Mobile or Genshin Impact at max settings), the device will warm up near the camera module. After about 20 minutes of heavy load, the system may throttle performance slightly to maintain safe temperatures. For casual users, this is unnoticeable, but hardcore gamers should be aware of this physical limitation.
Camera Capabilities: The "Hybrid" Zoom Explained
The S21 reuses the camera hardware from the S20 but improves the software processing (ISP).
1. Main Sensor (12MP): Excellent dynamic range and improved autofocus (Dual Pixel PDAF). Samsung's scene optimizer tends to saturate colors, producing "social media ready" images. 2. Ultrawide (12MP): One of the best in class. It features Super Steady video which acts like a gimbal, though it crops the frame slightly. 3. Telephoto (64MP): This is technically not an optical zoom lens. It uses a 1.1x optical lens and achieves "3x Hybrid Zoom" by cropping into the high-resolution 64MP sensor. While purists prefer optical glass, the results here are surprisingly sharp up to 10x.
Video Performance: The S21 can shoot 8K at 24fps, but the sweet spot is 4K at 60fps, where stabilization and autofocus perform best.
Battery Endurance & Charging Speeds
The 4000 mAh battery is standard for this size. With the 1080p screen and 5nm chip efficiency, the S21 generally lasts a full day of moderate use (4-5 hours Screen On Time). However, heavy 5G usage and 120Hz constant scrolling will drain the tank before evening.
Charging is capped at 25W wired and 15W wireless. In a market where competitors offer 65W or 120W charging, Samsung's 25W feels slow, taking over an hour to charge from 0 to 100%.
Market Value Guide (New vs Used)
Pricing fluctuates significantly based on condition and region. Below is a general estimation for the current market.
| Condition | Approximate Price Range | Recommendation |
| Brand New (Sealed) | $400 - $500 | Hard to find. Generally not recommended due to better newer options. |
| Refurbished (Excellent) | $220 - $280 | Best Value. Look for 1-year warranty offers. |
| Used (Private Seller) | $170 - $220 | High risk. Requires thorough inspection (see checklist below). |
Pre-owned Inspection Checklist
Buying a used S21 requires diligence. The AMOLED screen is the most expensive component, so verify its health first.
| Component | Test Procedure |
| OLED Burn-in | Dial *#0*# and select Red, Green, and Blue. Look for faint shadows of icons (status bar/keyboard). |
| Battery Health | Use the Samsung Members app > Diagnostics > Battery Status. It should say "Normal" or "Good". |
| Knox Status | Boot into Download Mode. Ensure "Warranty Void" is 0x0. If 0x1, Samsung Pay and Secure Folder will NOT work. |
Top Alternatives Comparison
1. Samsung Galaxy S20 FE 5G: Better if you absolutely need a MicroSD card slot and a bigger battery, but it has a weaker processor and shorter update lifespan. 2. Google Pixel 6a / 7a: Better for pure still photography and clean software, but lacks the S21's 120Hz display (6a is 60Hz, 7a is 90Hz) and telephoto lens. 3. Samsung Galaxy S21 FE: Released later, it offers similar specs but had launch pricing issues. If found cheaper than the S21, it's a viable option, though the build feels slightly cheaper.
Final Verdict
The Samsung Galaxy S21 has transitioned from a flagship to an unbeatable mid-range killer in the used market. It offers a premium display, competent cameras, and robust performance that budget phones today still struggle to match.
If you can live without expandable storage and the headphone jack, the S21 is a "Green Light" purchase recommendation, especially if found in refurbished condition for under $250. It remains one of the best compact Android phones available.