Asus Zenfone 9 vs Galaxy S21 5G

The Asus Zenfone 9, released in September 2022, and the Samsung Galaxy S21 5G, launched in January 2021, represent two distinct approaches to flagship Android smartphones. While both offer high-end performance and features, the Zenfone 9 emphasizes a compact form factor, whereas the Galaxy S21 5G provides a slightly larger display and a more traditional triple-camera setup. Both devices run on the Android operating system, offering a wide range of applications and customization.

When considering the long-term usability of these devices, their release timelines and software support are key factors.

• Release Timeline: The Asus Zenfone 9 was released in September 2022, making it a newer device compared to the Samsung Galaxy S21 5G, which launched in January 2021. This difference in release date impacts their respective software support cycles.
• Software Longevity: The Zenfone 9 was promised 2 years of major Android updates and 3 years of security updates, and is upgradable to Android 14. The Galaxy S21 5G, having launched earlier, received its final major Android OS update (Android 15) in May 2025, and security updates ceased in February 2026. This means the Zenfone 9 is likely to receive software support for a longer duration from the current date.
• Repairability: The Galaxy S21 5G generally has a higher repairability score, with some sources indicating it is relatively easy to disassemble and replace components like the battery and cameras. The Asus Zenfone 9 received a lower repairability score, with screen replacement noted as particularly challenging, though some internal components are modular.

Both smartphones deliver robust performance for daily tasks and demanding applications, though they utilize different generations of internal components.

• Processing Power: The Asus Zenfone 9 is equipped with a newer generation processor, which translates to efficient handling of demanding apps and smoother multitasking. The Galaxy S21 5G features a capable processor that provides fast response times and handles gaming and app switching effectively.
• Multitasking and Storage: Both devices offer 8GB of RAM in their base configurations, with the Zenfone 9 also having a 16GB RAM option, which can benefit users who frequently switch between many applications. Storage options for both typically start at 128GB, with 256GB variants available, utilizing fast UFS 3.1 storage for quick app loading and data transfer.
• Battery Behavior: The Zenfone 9 features a 4300 mAh battery, and users often report impressive battery life, sometimes outlasting larger phones. The Galaxy S21 5G has a 4000 mAh battery, and while it can last a full day for moderate use, heavy users, especially with the 120Hz display active, may find themselves needing to charge more frequently.

The visual experience on both devices is characterized by vibrant colors and smooth interactions, though there are differences in size and peak brightness.

• Display Technology and Clarity: Both smartphones feature AMOLED display technology, providing deep blacks and vibrant colors. The Zenfone 9 has a 5.9-inch Super AMOLED display, while the Galaxy S21 5G offers a slightly larger 6.2-inch Dynamic AMOLED 2X display. Both have a resolution of 1080x2400 pixels, resulting in sharp and clear visuals.
• Refresh Rate and Brightness: Both devices support a 120Hz refresh rate, contributing to smooth scrolling and responsive interactions. The Galaxy S21 5G's display can reach a peak brightness of 1300 nits, while the Zenfone 9 reaches 1100 nits, meaning the Galaxy S21 5G may offer slightly better visibility in bright outdoor conditions.
• Screen Protection: Both the Zenfone 9 and the Galaxy S21 5G utilize Corning Gorilla Glass Victus for enhanced screen durability against scratches and drops.

Both phones offer capable camera systems, but they differ in their configurations and stabilization technologies.

• Rear Camera Systems: The Asus Zenfone 9 features a dual-camera setup with a 50 MP main sensor that includes a 6-axis gimbal stabilization system, which is particularly effective for smooth video recording and improved low-light photography. It also has a 12 MP ultrawide lens. The Samsung Galaxy S21 5G comes with a versatile triple-camera system, including a 12 MP main lens with optical image stabilization (OIS), a 12 MP ultrawide lens, and a 64 MP telephoto lens offering 3x hybrid optic zoom.
• Photography Performance: The Zenfone 9's main camera is praised for detailed images with accurate colors and strong low-light performance, though some users note that image processing can sometimes be inconsistent. The Galaxy S21 5G's camera system is known for reliable performance in most conditions, with good detail and color reproduction, and its telephoto lens provides flexibility for zoomed shots.
• Video Recording and Front Camera: Both devices are capable of recording video at up to 8K resolution at 24fps. For selfies, the Zenfone 9 has a 12 MP front camera with autofocus, while the Galaxy S21 5G features a 10 MP front camera with dual pixel autofocus.