Samsung · Instant quote

Samsung Galaxy S21 5G

Carrier:

Storage:

Cosmetic Condition:

Functionality:

Accessories included:

Samsung Galaxy S21 5G launched in 2021 as the standard-size entry in Samsung's flagship line that year, sitting below the S21+ and S21 Ultra for buyers who wanted flagship silicon in a smaller, one-hand body. In the US it shows up as SM-G991U1 (unlocked retail) or SM-G991U (carrier-locked), and it still holds real resale value thanks to its Snapdragon 888 chip, 120Hz AMOLED screen, and IP68 rating — all still relevant specs years later. Whether it's a spare in a drawer or a phone you've upgraded away from, it's worth checking what it's worth before it sits idle. Pick your carrier and storage tier and condition above for a live cash offer, see how the process works, or head over if you're ready to sell your smartphone outright.

Confirm you have the Galaxy S21 5G

On the phone itself, go to Settings → About phone → Model number. That string tells you exactly which variant you're holding, and whether it's locked to a carrier or fully unlocked.

SM-G991U1

  • Unlocked US retail unit
  • Works across AT&T, T-Mobile, Verizon, and most GSM carriers
  • Typically the higher-value configuration for resale

SM-G991U

  • Carrier-locked unit sold through AT&T, T-Mobile, or Verizon
  • May require an unlock request from the original carrier before resale

Prefer a visual check? The S21 5G has a flat (not curved) display, a matte-plastic "Glasstic" back rather than glass, and a color-matched camera housing built into the corner of the frame rather than a separate raised module.

Core hardware

Processor

  • Qualcomm Snapdragon 888 (US market chipset)

Memory

  • 8GB RAM, soldered and not upgradable after purchase

Storage

  • 128GB, 256GB, or 512GB, fixed at time of purchase
  • No microSD expansion slot
  • Higher storage tiers move resale value the most

Cameras

  • 12MP wide, 12MP ultrawide, 64MP telephoto (hybrid optical zoom)
  • 10MP front-facing camera

Display & audio

Display

A 6.2-inch Dynamic AMOLED 2X panel at FHD+ resolution with adaptive refresh up to 120Hz, protected by Corning Gorilla Glass Victus. Flat, not curved, which makes screen protectors and repairs simpler than on the Ultra.

Audio

Stereo speakers tuned with AKG, with Dolby Atmos support. There is no headphone jack, so audio out relies on USB-C or Bluetooth.

Security

An in-display ultrasonic fingerprint sensor handles unlocking, alongside 2D facial recognition as a faster but less secure fallback.

Ports & connectivity

The Galaxy S21 5G keeps things simple: a single USB-C port for charging and data, no expandable storage, and full sub-6GHz 5G support.

Wired
  • USB-C (charging and data)
Wireless
  • 5G (sub-6GHz) and 4G LTE
  • Wi-Fi 6
  • Bluetooth 5.0
  • NFC for contactless payments

Snapdragon 888 120Hz AMOLED 5G IP68 rated Ultrasonic fingerprint Wireless charging USB-C

Battery, build & more

Battery

A 4,000mAh battery with wired fast charging, wireless charging, and reverse wireless charging for accessories like earbuds. No charger is included in the box.

Build

An aluminum frame with a Glasstic (polycarbonate) back rather than glass, and an IP68 rating for dust and water resistance.

Finishes

Launched in Phantom Gray, Phantom White, and Phantom Violet, with Phantom Pink offered in select markets.

Software

Shipped with Android 11 and One UI 3.1. Samsung's update policy for this generation covers several years of security patches and OS upgrades, though how many remain depends on the unit's age today.

Frequently asked questions

01 How do I find the model number or exact configuration?
Go to Settings → About phone → Model number to see whether you have an SM-G991U1 (unlocked) or SM-G991U (carrier-locked) unit. The same screen, or Settings → About phone → Status, shows your storage tier if you tap Storage in Settings directly. Knowing the exact model and storage capacity ahead of time makes the configuration picker above faster to fill out accurately.
02 How do I tell it apart from the Galaxy S21+?
Size and weight are the fastest tells. The S21 5G is the smaller of the two, with a 6.2-inch flat display, while the S21+ carries a 6.7-inch screen and a noticeably heavier, larger body. Both share the same flat-display, Glasstic-back design language, so if you're unsure, check Settings → About phone → Model number: the S21+ shows an SM-G996 prefix instead of SM-G991.
03 Can I sell it with damage, a cracked screen, or a weak battery?
Yes. Select the condition that matches the phone honestly in the picker above, and the quote adjusts accordingly. A cracked screen, a battery that no longer holds charge well, or a phone that won't power on can still carry value, though a working device will always bring in more. The one non-negotiable is your Google account and any screen lock: it must be fully removed via factory reset before shipping, since a device still tied to an account or Google's Factory Reset Protection cannot be resold or refurbished.
04 What raises the trade-in value the most?
An unlocked, higher-storage unit in clean cosmetic condition brings the strongest offer. Storage tier matters (512GB and 256GB units outvalue 128GB), and an unlocked SM-G991U1 is generally worth more than a carrier-locked SM-G991U since it works on any network. A screen free of cracks, a battery that still holds a reasonable charge, and having the original box or charger on hand all help, though none of those are required to sell.
05 How do I erase it, remove my accounts, and get paid?
Start with a backup of anything you want to keep, then go to Settings → Accounts and backup → remove your Samsung account and your Google account. Next, go to Settings → General management → Reset → Factory data reset and confirm. This clears Factory Reset Protection so the phone can be activated by its next owner. Once you've packed it up, shipping is free and insured, and payment goes out after inspection and testing, by PayPal, Venmo, Zelle, CashApp, or check. Full details on how data is wiped are covered in our data erasure protocols.