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In short, yes. The case will fit on the iPhone X or iPhone XS; however, there are a few important design elements that differ between these devices that will affect where the case’s cutouts are for buttons, audio grilles, and the charging port. This poses some functionality issues, so here is what to expect when fitting one of these iPhone 11 cases onto an iPhone X or XS.
Camera Area: The cameras of these devices differ. The iPhone 11 has three camera lenses configured in a square, but the iPhone X and iPhone XS's camera is a smaller, vertical oval. While the case will fit around the camera, there will be open space to the right of the X’s cameras, but it's only an aesthetic issue.
Left Side: For the iPhone 11, the volume buttons and silent toggle switch are placed lower on the side. Because of this, the case’s cutouts for these buttons will not perfectly line up with your iPhone X. This will make accessing these more challenging.
Right Side: Of most concern, the iPhone X’s unlock button and SIM card tray are unaligned with the iPhone 11 case. This will likely be a very annoying issue to deal with, as the unlock button won’t be easily accessible.
Charging Port: For the most part, the bottom of the iPhone 11 case poses no real issue for charging. The charging port cutout of the case lines up well with the port on the iPhone X and XS.
While iPhone 11 cases will technically fit the iPhone X and iPhone XS, the updates to the exterior buttons would make using 11 cases for the X frustrating, and these functionality issues will be a deal breaker for most.
Luckily for you, i-Blason has many popular case styles for the iPhone X and iPhone XS, including the 20ft drop tested Ares case, the cute and functional Cosmo Snap, and even a battery case, so you can find your perfect fit.