No, your OnePlus 9 Pro case won't fit the Galaxy S21 Ultra
The OnePlus 9 Pro (163.2×73.6mm) and Galaxy S21 Ultra (165.1×75.6mm) differ too much for cases to be compatible.
Does a OnePlus 9 Pro Case Fit Galaxy S21 Ultra?
Last verified: March 2026
No, a OnePlus 9 Pro case will not fit the Galaxy S21 Ultra. The phones have different dimensions that make cases incompatible.
Your OnePlus 9 Pro case will NOT fit the Galaxy S21 Ultra. Here's why:
- •Height differs by 1.9mm — case won't fit
- •Width differs by 2.0mm — case won't fit
- •Thickness differs by 0.2mm — may affect fit
- •Camera bump size differs significantly
- •Camera bump protrusion differs by 2.8mm — case lip may not protect camera
- •Old phone has alert slider — new phone does not
| Spec | OnePlus 9 Pro | Galaxy S21 Ultra | Diff |
|---|---|---|---|
| Height | 163.2mm | 165.1mm | Galaxy S21 Ultra +1.9mm |
| Width | 73.6mm | 75.6mm | Galaxy S21 Ultra +2.0mm |
| Thickness | 8.7mm | 8.9mm | Galaxy S21 Ultra +0.2mm |
| Camera Layout | vertical-quad | vertical-quad | Same |
| Port | usb-c | usb-c | Same |
Button & Port Alignment
- •Old phone has alert slider — new phone does not
Your OnePlus 9 Pro 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 9 Pro
Qi only
10W 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 9 Pro and Galaxy S21 Ultra the same size?
OnePlus 9 Pro measures 163.2×73.6×8.7mm while Galaxy S21 Ultra measures 165.1×75.6×8.9mm. They are different sizes.
Can I use a OnePlus 9 Pro screen protector on Galaxy S21 Ultra?
Same screen size (6.8") but body width differs by 2.0mm — verify bezel alignment before buying.
What's different between OnePlus 9 Pro and Galaxy S21 Ultra dimensions?
The height differs by 1.9mm, the width by 2.0mm, and thickness by 0.2mm.
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 9 Pro, so cases are not interchangeable.
Will OnePlus 9 Pro 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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