Product Overview
The Samsung Galaxy S21 is a compact 6.2‑inch flagship phone that balances performance and size. It features a 120 Hz Dynamic AMOLED display, a triple‑camera system with 64 MP telephoto, and the Exynos 2100 or Snapdragon 888 processor (depending on region). The Contour Cut camera housing wraps around the frame, giving the S21 a distinctive look. It supports 5G, wireless charging, and an ultrasonic fingerprint sensor. The phone runs One UI 5.1 on Android 13 and is upgradeable to One UI 6. It’s available in Phantom Gray, Phantom White, Phantom Violet, and Phantom Pink.
Key Features
- 6.2‑inch 120 Hz AMOLED Display: The Full HD+ screen adapts its refresh rate between 48 Hz and 120 Hz to balance smoothness and battery life. It’s bright and sharp with HDR10+ support.
- Triple Camera System: 12 MP main (f/1.8, OIS), 12 MP ultra‑wide (f/2.2, 120°), and 64 MP telephoto (f/2.0, 3x hybrid zoom). The telephoto lens captures detailed shots at distance and enables Space Zoom up to 30x.
- Single Take 2.0: Press the shutter once, and the camera captures a variety of photos and video clips simultaneously – from boomerangs to filtered stills – so you can pick the best result later.
- Portrait Video: Record video with real‑time background blur. Adjust the strength of the effect before or after shooting.
- Ultrasonic Fingerprint Sensor: Built into the lower portion of the display, it’s faster and more secure than optical sensors. It also works with slightly damp fingers.
- 5G Connectivity: Sub‑6 and mmWave support depending on the model. You get fast downloads and low latency for streaming and gaming.
- Wireless PowerShare: Use the S21 to wirelessly charge another phone, Galaxy Buds, or a Galaxy Watch by placing them on the back of the device.
How to Use
What’s in the Box
- Samsung Galaxy S21 (with a pre‑installed screen protector on some models)
- USB‑C to USB‑C cable
- SIM card ejector tool
- Quick‑Start Guide and warranty card
No charger, earphones, or case are included. Use any USB‑C PD charger (25W recommended for fast charging).
First‑Time Setup
- Press and hold the Side button (right edge) until the Samsung logo appears.
- Select your language, connect to Wi‑Fi, and sign in with your Google account and Samsung account.
- Use Smart Switch to transfer data from an old Android phone or iPhone. You can connect both phones with a USB‑C cable or do a wireless transfer.
- Once on the Home screen, go to Settings > Software update and install any pending updates.
- In Settings > Display, set Motion smoothness to Adaptive for 120 Hz scrolling, or Standard for 60 Hz to save battery.
Buttons, Ports & Fingerprint Sensor
| Component | Location | Function |
|---|---|---|
| Side button / Bixby | Right edge | Press to wake/sleep. Double‑press for camera. Press and hold for Bixby (or power menu, customizable in Settings > Advanced features > Side key). |
| Volume rocker | Right edge (above Side button) | Adjust media and ringer volume. |
| USB‑C port | Bottom edge | Charging, data transfer. No headphone jack. |
| SIM tray | Bottom edge (left side) | Holds one nano‑SIM. eSIM is also supported on some models. No microSD slot. |
| Fingerprint sensor | Under the display (lower centre) | Press firmly on the screen to unlock. Register up to four fingerprints in Settings > Biometrics and security > Fingerprints. |
Camera Tips
- Single Take: Tap the Single Take icon, then press the shutter. Move the phone slowly for about 5–10 seconds. The phone captures multiple photos and video clips. Swipe through them afterwards.
- 30x Space Zoom: Pinch to zoom or tap the zoom presets (0.5x, 1x, 3x, 10x, 20x, 30x). Use a tripod or steady hand at high zoom. The telephoto lens provides 3x hybrid optical zoom.
- Portrait mode: Select Portrait from the mode bar. Adjust background blur before or after taking the shot. Works with both the main and telephoto cameras.
- Pro Video mode: Swipe to More > Pro Video. Manually control ISO, shutter speed, focus, white balance, and audio direction (front, rear, or surround).
- Quick launch: Double‑press the Side button to open the camera, even when locked.
Battery & Charging
- Battery capacity: 4,000 mAh. Lasts a full day with moderate use.
- Wired charging: Supports 25W USB‑C PD fast charging (charger sold separately). A 30‑minute charge gives about 50%.
- Wireless charging: Up to 15W with a Qi‑compatible pad. The S21 also supports Wireless PowerShare, which lets you charge another device (e.g., Galaxy Buds) on the back of the phone.
- Battery protection: Go to Settings > Battery and device care > Battery > More battery settings > Protect battery to cap charging at 85% for long‑term battery health.
Troubleshooting & Common Problems
| Problem | Likely Cause | What to Try |
|---|---|---|
| Fingerprint sensor slow or not recognizing | Dirty screen, or dry finger | Clean the screen and your finger. Delete and re‑register fingerprints. Register the same finger twice. |
| Camera app crashes | Software glitch, or low storage | Restart the phone. Clear the camera app cache: Settings > Apps > Camera > Storage > Clear cache. |
| Phone overheats during gaming | Intensive graphics or charging | Remove the case. Lower the game’s graphics settings. Avoid gaming while charging. |
| Battery drains quickly | 120 Hz display, or rogue apps | Switch to 60 Hz motion smoothness. Check Settings > Battery and device care > Battery for app usage. Turn on Dark mode. |
| Wi‑Fi disconnects often | Router or signal issue | Restart the router and phone. Forget the network and reconnect. Turn off Wi‑Fi power saving mode in Settings > Connections > Wi‑Fi > Advanced. |
| No sound during calls | Earpiece speaker blocked, or Bluetooth connected | Check that Bluetooth is off, or switch audio to the earpiece. Clean the earpiece grille with a soft brush. |
Common Problems Quick List
- Screen flickering: This may occur at low brightness with 120 Hz enabled. Switch to 60 Hz in Display settings to test. If it persists, update the software.
- SIM card not detected: Remove and re‑insert the SIM tray. Restart the phone. If the problem continues, the SIM card may be faulty.
- Wireless charging not working: Ensure the phone is centred on the charger. Remove any thick cases or metal attachments. The S21 charges at 15W only with Samsung‑certified pads.
Frequently Asked Questions
- Does the Galaxy S21 have a headphone jack?
No. Use Bluetooth headphones or a USB‑C to 3.5 mm adapter. - Can I expand storage with a microSD card?
No, the S21 does not have a microSD card slot. Choose the 128 GB or 256 GB variant at purchase. - Is the phone waterproof?
It has an IP68 rating, meaning it can withstand submersion in fresh water up to 1.5 metres for 30 minutes. Avoid salt water and chlorinated pools. - How do I take a screenshot?
Press the Side button and Volume Down button at the same time. For a scrolling screenshot, tap the arrow icon after capturing. - Does the S21 support wireless charging?
Yes, up to 15W fast wireless charging, and it can also charge other devices via Wireless PowerShare. - How do I reset the phone?
Go to Settings > General management > Reset > Factory data reset. You’ll need your lock screen PIN or password.
Tips
- Use Director’s View: In the Camera app, swipe to More > Director’s View. You’ll see live thumbnails from all three lenses and can switch between them while recording video.
- Enable Edge Panels: Go to Settings > Display > Edge panels for quick access to apps, tools, and contacts from a swipeable tab on the right edge.
- Extend battery life: Use Adaptive battery and turn on Dark mode. The AMOLED screen saves power with dark pixels.
- Customise the Side key: Go to Settings > Advanced features > Side key and set Double press to open any app, and Press and hold to show the power off menu instead of Bixby.
- Keep the phone updated: Samsung provides security patches and One UI updates. Check Settings > Software update regularly.
Safety Information
- Charging: Use Samsung‑certified or reputable third‑party USB‑C PD chargers. Avoid using the phone while fast‑charging in direct sunlight or very hot environments.
- Battery: Do not puncture, drop, or expose the battery to high heat. If the battery swells, stop using the phone immediately and contact Samsung support.
- Screen: The S21 uses Gorilla Glass Victus on the front. It’s durable, but a screen protector adds extra protection against scratches.
- Water resistance: The IP68 rating applies to fresh water only. Dry the USB‑C port before charging if the phone gets wet.
- Repairs: The back glass is glued on and difficult to remove. Repairs should be performed by Samsung or an authorised service centre.
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Copyright 2026 productsmanuals.com All rights reserved. This Samsung Galaxy S21 SM‑G991B manual is original content and may not be copied, republished, or redistributed without written permission. Samsung, Galaxy, and the Samsung logo are trademarks of Samsung Electronics. This guide is unofficial and not affiliated with Samsung.
