Apple doesn’t consider iPhone 17 Pro cases compatible with iPhone 18 Pro, because the new phone’s camera plateau is slightly thicker, Apple told Daring Fireball’s John Gruber. By his caliper, the difference is one-tenth of a millimeter, and in his testing the old cases fit the new phones “perfectly”.
So if you’ve just upgraded, your old case will almost certainly go on. Apple just won’t vouch for it, and the lip that guards the lenses sits a fraction lower than on a case made for the new phone.
What Apple told Gruber
Gruber, who reviewed both sizes before launch, raised it in his September 17 review. “I asked Apple if they’re stating that 18 Pro models are case-compatible with the iPhone 17 Pro, and they are not, because the 18 Pro camera plateaus are slightly thicker this year,” he wrote.
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He then measured both phones. “I measured with a digital caliper and the difference is one-tenth of a millimeter: 11.5mm vs. 11.4mm. So Apple has raised the plateau guard lip on its own 18 Pro cases by one-tenth of a millimeter.” Those are his measurements, not figures Apple publishes. Apple’s tech specs give only the depth of the phone body, 8.75mm for both iPhone 18 Pro models, and don’t list the plateau.
Everything else is unchanged. “Per Apple’s own specs, they’re precisely the same width, height, and thickness,” Gruber wrote, and he found that 17 Pro cases fit 18 Pro phones, and 18 Pro cases fit 17 Pro phones, with no problems in either direction. His conclusion is that it’s “close enough to declare that you can use 17 Pro cases on 18 Pro iPhones and vice-versa.”
What Apple’s store says
Apple’s own listings match what it told Gruber. The iPhone 17 Pro Silicone Case with MagSafe, still on sale at $49, names only “iPhone 17 Pro” under Compatibility. The iPhone 18 Pro Silicone Case with MagSafe, also $49, names only “iPhone 18 Pro”. Neither page lists the other phone.
What to do with your old case
For most people, the sensible answer is to keep using it. Gruber found a proper fit, and the width, height and thickness that decide whether a case goes on are the same.
The one thing to watch is the camera. The raised lip around a case’s camera opening is there so the lenses don’t touch the table when the phone lies on its back. On an iPhone 18 Pro, a 17 Pro case gives that lip one-tenth of a millimeter less clearance. A quick check is to lay the phone in its case on a flat, hard surface, back down, and look from the side: if the lip still holds the plateau clear, it’s doing its job. If the plateau rests on the surface or rocks, a case made for the 18 Pro is the safer choice.
If you do replace it, the old case isn’t wasted. It’s still a case Apple lists for iPhone 17 Pro, so it can go with your old phone if you’re selling it or handing it down. It also works the other way: an 18 Pro case fits a 17 Pro, according to Gruber, so a family sharing phones across the two years doesn’t need to keep them strictly paired.
If you’ve already bought a new case from Apple and would rather keep your old one, Apple’s US store gives you 14 calendar days from the date you receive it to return it in its original condition, with all its packaging. Our guide to Apple’s return window explains how that clock works.
Pro Max owners too
Gruber’s finding covers both sizes. He writes about “the 18 Pro camera plateaus” in the plural, and Apple’s answer applied to “18 Pro models”. The iPhone 18 Pro Max body measures 163.4 by 78.0 by 8.75mm in Apple’s specs. If you’re still deciding which accessories are worth buying at launch, our accessories guide covers what Apple sells.
