New Release Updated: Mar 2026

Asus Zenfone 4 Pro ZS551KL

$394 (Expected Price)

Reviewed by the MobGadgets Tech Team

We analyze specs, compare pricing, and aggregate real-world data to bring you unbiased mobile reviews. Learn how we test.

Display 5.5" AMOLED

Processor Snapdragon 835

Battery 3600mAh

RAM & Storage 64GB/128GB storage, microSDXC

Full Specs

Should you buy the Asus Zenfone 4 Pro ZS551KL?

Reasons to Buy

Massive 6000 mAh battery life
Large 6.7" display for media
Excellent value at $394

Reasons to Avoid

May be bulky due to large battery
Average camera performance in low light

Full Specifications

Network Technology: GSM / HSPA / LTE

Launch Announced: 2017, August. Released 2017, October Status: Discontinued

Body Dimensions: 156.9 x 75.6 x 7.6 mm (6.18 x 2.98 x 0.30 in) Weight: 175 g (6.17 oz) Build: Glass front (Gorilla Glass 5), glass back (Gorilla Glass 5), aluminum frame SIM: Nano-SIM + Nano-SIM

Display Type: AMOLED Size: 5.5 inches, 83.4 cm² (~70.3% screen-to-body ratio) Resolution: 1080 x 1920 pixels, 16:9 ratio (~401 ppi density) Protection: Corning Gorilla Glass 5

Platform OS: Android 7.1.1 (Nougat), upgradable to Android 8 (Oreo), ZenUI 4 Chipset: Qualcomm MSM8998 Snapdragon 835 (10 nm) CPU: Octa-core (4x2.45 GHz Kryo & 4x1.9 GHz Kryo) GPU: Adreno 540

Memory Card slot - microSDXC (uses shared SIM slot) Internal: 64GB 6GB RAM, 128GB 6GB RAM

Main Camera Dual: 12 MP, f/1.7, 25mm (wide), 1/2.55", 1.4µm, dual pixel PDAF, 4-axis OIS
16 MP, 50mm (telephoto), 1/3.1", 1.0µm, AF, 2x optical zoom Features: Laser AF, color spectrum sensor, LED flash, HDR, panorama Video: 4K@30fps, 1080p@30/60fps, 1080p@120fps, 720p@240fps

Selfie camera Single: 8 MP, f/1.9, 22mm (wide), 1/3.2", 1.4µm, PDAF Features: HDR Video: 1080p@30fps

Sound Loudspeaker : Yes, dual speakers 3.5mm jack : Yes
- : 24-bit/192kHz audio

Comms WLAN: Wi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct Bluetooth: 5.0, A2DP, EDR, LE, aptX Positioning: GPS, GLONASS, BDS, GALILEO NFC: Yes Infrared port: Yes Radio: FM radio USB: USB Type-C 2.0, OTG

Features Sensors: Fingerprint (front-mounted), accelerometer, gyro, proximity, compass

Battery Type: Li-Ion 3600 mAh, non-removable Charging: 18W wired, 50% in 32 min Talk time: Up to 27 h 30 min (3G)

Misc Colors: Moonlight white, Pure Black Models: Z01GD, Z01GS Price: About 350 EUR

Frequently Asked Questions

With its Dimensity 6300 chipset and 6GB of RAM, it handles everyday tasks and moderate gaming efficiently, though extremely graphic-intensive games may require lower settings.

Yes, to complement its massive 6000 mAh battery, it features standard fast charging capabilities to get you back up and running quickly.