No, your OnePlus 12 case won't fit the Galaxy S21 Ultra
The OnePlus 12 (164.3×75.8mm) and Galaxy S21 Ultra (165.1×75.6mm) differ too much for cases to be compatible.
Does a OnePlus 12 Case Fit Galaxy S21 Ultra?
Last verified: March 2026
No, a OnePlus 12 case will not fit the Galaxy S21 Ultra. The phones have different dimensions that make cases incompatible.
Your OnePlus 12 case will NOT fit the Galaxy S21 Ultra. Here's why:
- •Body dimensions are nearly identical, but the camera cutout is incompatible (circular-triple vs vertical-quad)
| Spec | OnePlus 12 | Galaxy S21 Ultra | Diff |
|---|---|---|---|
| Height | 164.3mm | 165.1mm | Galaxy S21 Ultra +0.8mm |
| Width | 75.8mm | 75.6mm | OnePlus 12 +0.2mm |
| Thickness | 9.2mm | 8.9mm | OnePlus 12 +0.3mm |
| Camera Layout | circular-triple | vertical-quad | Different |
| Port | usb-c | usb-c | Same |
Button & Port Alignment
- •Old phone has alert slider — new phone does not
Your OnePlus 12 case won't fit the Galaxy S21 Ultra. Find the right case:
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Size Comparison
Wireless Charging & MagSafe
Wireless chargers work with both phones, but magnetic snap varies.
- Both devices support wireless charging. Standard Qi/Qi2 chargers work with either phone.
OnePlus 12
Qi only
15W max
Galaxy S21 Ultra
Qi only
15W max
MagSafe cases are NOT cross-compatible between these devices — the case body is shaped to each phone, even though the internal magnet ring may be the same.
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Frequently Asked Questions
Are OnePlus 12 and Galaxy S21 Ultra the same size?
OnePlus 12 measures 164.3×75.8×9.2mm while Galaxy S21 Ultra measures 165.1×75.6×8.9mm. They are different sizes.
Can I use a OnePlus 12 screen protector on Galaxy S21 Ultra?
Same screen size (6.8") with minimal width difference — should fit.
What's different between OnePlus 12 and Galaxy S21 Ultra dimensions?
The height differs by 0.8mm, the width by 0.2mm, and thickness by 0.3mm. The camera module layout is also different.
Do I need a new case for Galaxy S21 Ultra?
Yes, you'll need a new case. The Galaxy S21 Ultra has different dimensions than the OnePlus 12, so cases are not interchangeable.
Will OnePlus 12 accessories work with Galaxy S21 Ultra?
Chargers and cables are compatible since both phones use the same usb-c port. Both support wireless charging, so wireless chargers work with either phone. Cases and screen protectors depend on exact dimensions — check our compatibility results above.
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