Apple lists the iPhone 18 Pro at 150.0 x 71.9 x 8.75 mm, which is exactly what it listed for the iPhone 17 Pro, and the iPhone 18 Pro Max at 163.4 x 78.0 x 8.75 mm, exactly what it listed for the 17 Pro Max. If you can hold either of last year’s Pro models, you can settle the size half of this decision before pre-orders open, with no guesswork.
The one line that moved is weight. The new 6.3-inch Pro is 211 g against 206 g, and the new Pro Max is 249 g against 233 g. Both generations share an 8.75 mm thickness and the same display diagonals and resolutions, so a 17 Pro in your hand is an accurate stand-in for footprint, screen size and reach, and a slightly light one for mass.
Key facts: four phones, two footprints
| Model | Height x width x depth | Weight | Display |
|---|---|---|---|
| iPhone 18 Pro | 150.0 x 71.9 x 8.75 mm | 211 g | 6.3 inches, 2622 x 1206 |
| iPhone 17 Pro | 150.0 x 71.9 x 8.75 mm | 206 g | 6.3 inches, 2622 x 1206 |
| iPhone 18 Pro Max | 163.4 x 78.0 x 8.75 mm | 249 g | 6.9 inches, 2868 x 1320 |
| iPhone 17 Pro Max | 163.4 x 78.0 x 8.75 mm | 233 g | 6.9 inches, 2868 x 1320 |
Every figure there is from Apple’s own specifications. The two new phones also share a frame description with last year’s pair, an aluminum unibody, with Apple describing the 18 Pro generation as the same design carried over with a new rear finish.
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The gap between the two sizes has widened
Because both new models gained weight but not at the same rate, the penalty for choosing the bigger phone is heavier this year than last. The 17 Pro and 17 Pro Max were 27 g apart. The 18 Pro and 18 Pro Max are 38 g apart, which is 11 g more of a difference for the same 13.4 mm of extra height and 6.1 mm of extra width.
| Comparison | 2025 pair | 2026 pair |
|---|---|---|
| Weight gap between the sizes | 27 g | 38 g |
| Height gap between the sizes | 13.4 mm | 13.4 mm |
| Width gap between the sizes | 6.1 mm | 6.1 mm |
| Thickness, all four phones | 8.75 mm | 8.75 mm |
| Weight added year over year, small Pro | Not applicable | 5 g |
| Weight added year over year, Pro Max | Not applicable | 16 g |
For scale, 38 g is a little over the weight of an AirPods 5 charging case, which Apple lists at 32.3 g. It is the one part of the size trade-off that a spec sheet describes poorly and a hand describes instantly.
How to size-test before pre-orders open
- Borrow a 17 Pro for the 6.3-inch decision or a 17 Pro Max for the 6.9-inch one. Apple no longer sells either model, and its comparison page now lists the 17 Pro as available through authorized resellers.
- Judge width first. The 6.1 mm between 71.9 mm and 78.0 mm is what your thumb has to cross and what a pocket takes sideways.
- Add the missing mass mentally: 5 g on the small Pro, 16 g on the Pro Max. Neither changes the footprint.
- Ignore thickness. All four phones are 8.75 mm, so a case is the only thing that will change it.
- Trust the screen test. The diagonals and resolutions are unchanged from last year, so what fits on a 17 Pro display is what fits on an 18 Pro display.
If the nearest phone you can borrow is an iPhone 16 Pro, the reference is less exact. Apple lists it at 149.6 x 71.5 x 8.25 mm and 199 g, so the new 6.3-inch Pro is 0.4 mm taller, 0.4 mm wider, 0.5 mm thicker and 12 g heavier than what you are holding.
What the size choice does not affect
Nothing on the rest of the specification. The A20 Pro, the three 48MP rear cameras, the 18MP front camera, the video formats, Wi-Fi 7, Bluetooth 6, dual eSIM, IP68 to 6 meters, all four storage tiers up to 2TB and all four colors are listed identically for both sizes, as our launch-day specification rundown sets out.
What the size does change is the battery rating, 45 hours of video playback against 36, and the price, $100 at every tier. Our Pro against Pro Max comparison and our price breakdown cover both, and the 18 Pro against 17 Pro comparison covers what else changed in a year.
What has not been confirmed
- Whether a 17 Pro or 17 Pro Max case fits the matching new model. Identical published dimensions are not a case-compatibility statement, and Apple has not issued one.
- The camera plateau dimensions on either generation, which is where a case would bind if anything does.
- Where the extra 5 g and 16 g sit. Apple publishes no component weights and no battery capacity.
- Whether Apple Stores will have both sizes on display before September 18, or in every finish.
- Any screen-to-body ratio, bezel width or one-handed-reach figure for either model.
Pre-orders open at 5 a.m. PT on Saturday, September 12, which is 12:00 UTC, and both sizes reach stores on Friday, September 18, with 20 more countries on September 25. The size you pick at checkout is the one choice in the basket that no software update or accessory can change later.
