The iPhone 18 Pro Max measures 6.43 × 3.07 × 0.34 inches (163.4 × 78 × 8.75 mm). It weighs 8.78 ounces (249 g).
This guide covers the iPhone 18 Pro Max size, how it compares with other models, its shape, case fit, price and key features.
Table of Contents
iPhone 18 Pro Max Dimensions and Weight
Apple lists the exact iPhone 18 Pro Max dimensions on its official specs page. Here is the quick answer.
Measurement
Inches
Millimeters
Centimeters
Height
6.43 in
163.4 mm
16.34 cm
Width
3.07 in
78.0 mm
7.80 cm
Thickness
0.34 in
8.75 mm
0.875 cm
Weight
8.78 oz
249 g
0.249 kg
iPhone 18 Pro Max Height, Width and Thickness
The phone is a little over 6.4 inches tall and about 3 inches wide. Its footprint is roughly 19.8 square inches. That is about 18% more surface than the iPhone 18 Pro, which covers about 16.7 square inches.
iPhone 18 Pro Max Screen Size
The display is 6.9 inches across the diagonal, at 2868 × 1320 pixels and 460 pixels per inch. Apple notes that the corners are rounded. Measured as a plain rectangle, the screen is 6.86 inches.
The screen fills about 91% of the front, so there is very little wasted border.
Does the Size Change by Phone?
Apple says size and weight vary by configuration and manufacturing process. A small difference between two units is normal.
iPhone 18 Pro Max Size vs iPhone 18 Pro, 17 Pro Max and iPhone Duo
Here is how the iPhone 18 Pro Max size compares with nearby models.
Model
Height × Width × Thickness
Weight
iPhone 18 Pro Max
163.4 × 78 × 8.75 mm
249 g
iPhone 18 Pro
150 × 71.9 × 8.75 mm
211 g
iPhone 17 Pro Max
163.4 × 78 × 8.75 mm
233 g
iPhone Duo (open)
164.6 × 117.8 × 5.2 mm
254 g
iPhone Duo (closed)
117.8 × 84.1 × 11.3 mm
254 g
The Pro Max is 13.4 mm taller, 6.1 mm wider and 38 g heavier than the Pro. Both share the same thickness.
Next to the iPhone 17 Pro Max, the size is the same. Only the weight changed: it went up by 16 g.
Is the iPhone 18 Pro Max the Heaviest iPhone?
It is the heaviest non-folding iPhone. The 14 Pro Max weighed 240 g. Only the foldable iPhone Duo, at 254 g, weighs more.
iPhone 18 Pro Max Shape, Fit and Case Guide
Size is only half the story. Shape and fit decide how the phone feels every day.
iPhone 18 Pro Max Shape and Build
The iPhone 18 Pro Max is a flat, rectangular slab with rounded corners. It has an aluminum unibody frame, Ceramic Shield 2 on the front and Ceramic Shield on the back. It carries an IP68 rating for water and dust, at up to 6 meters for 30 minutes.
One-Handed Use and Pocket Fit
At 78 mm wide, the phone is a wide reach for a small hand. Most people use two hands for the top corners of the screen. The Dynamic Island sits at the top, so typing near it takes a longer stretch.
For pockets, remember that a case adds thickness. Test the fit with your case on.
Will an iPhone 17 Pro Max Case Fit the iPhone 18 Pro Max?
The outer dimensions match, but a case is molded around more than size. The camera cutout, button positions, speaker holes and MagSafe magnet ring must all line up. Apple has not confirmed cross-fit, so check the case maker’s compatibility list before you buy.
Screen protectors follow the same rule. Buy one made for the 18 Pro Max by name.
iPhone 18 Pro Max Price and Key Features
iPhone 18 Pro Max Price in the USA
Apple announced the phones on Sept. 9, 2026, and they went on sale on Sept. 18. In the USA, the Pro Max starts at $1,299. The Pro starts at $1,199.
Storage options are 256GB, 512GB, 1TB and 2TB. Colors are Black, Silver, Glacier and Burgundy.
Camera, Chip and Battery
Chip: A20 Pro, with a 6-core CPU and 7-core GPU.
Main camera: 48MP with variable aperture, from ƒ/1.48 to ƒ/4.0.
Other cameras: 48MP ultra wide and 48MP 4x telephoto, plus an 18MP front camera.
Battery: Up to 45 hours of video playback, per Apple’s testing.
Charging: About 50% in 15 minutes with a 60W adapter. MagSafe and Qi2 charge at up to 25W.
Ports and network: USB-C, Wi-Fi 7, Bluetooth 6 and eSIM only.
The phone runs iOS 27. Siri AI is in beta and starts in English.
Should You Pick the Pro or the Pro Max?
Pick the Pro Max if you want the biggest screen and the longest battery life. Pick the Pro if you want a lighter phone and easier one-handed use.
iPhone 18 Pro Max Dimensions FAQs
What Are the iPhone 17 Pro Max Dimensions?
The iPhone 17 Pro Max measures 163.4 × 78 × 8.75 mm (6.43 × 3.07 × 0.34 in). It weighs 233 g (8.22 oz).
What Is the iPhone 18 Pro Max Like?
It is a 6.9-inch flagship with an A20 Pro chip, a 48MP variable-aperture camera and up to 45 hours of video playback. It starts at $1,299 in the USA.
What Is the Shape of the iPhone 18 Pro Max?
It is a rectangular slab with rounded corners and an aluminum frame. The front has Ceramic Shield 2 glass, and the back has Ceramic Shield.
Is the iPhone 17 Pro Max the Same Size as the iPhone 18 Pro Max?
Yes, by measurement. Both are 163.4 × 78 × 8.75 mm. The 18 Pro Max is 16 g heavier.
Is the iPhone 18 Pro Max the Same Size as the iPhone 18 Pro?
No. The Pro Max has a 6.9-inch screen and weighs 249 g. The Pro has a 6.3-inch screen and weighs 211 g. Only the thickness matches.
Will a 17 Pro Max Case Fit an 18 Pro Max?
It may not. The body size is the same, but camera, button and MagSafe details can differ. Check the case maker’s compatibility list first.
Conclusion
The iPhone 18 Pro Max dimensionsare 6.43 × 3.07 × 0.34 inches and 8.78 ounces. It matches the 17 Pro Max in size, but it is heavier. Check the case model before you buy, and pick the Pro Max if screen size and battery life matter most.
Elizabeth Queen is a Owner and consumer research writer at HowLongThings.com, specializing in product lifespan, durability, and everyday household research. She’s passionate about helping readers make smarter, longer-lasting buying decisions.
