The iPhone 18 Pro Max retains the same external dimensions as its predecessor but weighs noticeably more: it measures 163.4mm x 78mm x 8.75mm and is 16 grams heavier than the iPhone 17 Pro Max.
iPhone 18 Pro Max weight and dimensions
Apple lists the iPhone 18 Pro Max at 249 grams, up from 233 grams for the iPhone 17 Pro Max, making it the heaviest non-folding iPhone to date. By comparison, the iPhone 14 Pro Max weighed 240 grams. Despite the increase, the iPhone 18 Pro Max remains slightly lighter than the iPhone Duo, which weighs 254 grams and is Apple’s heaviest iPhone overall.
Other model changes
The iPhone 18 Pro also gained weight: it now weighs 211 grams, up from 206 grams for the prior-generation model. Physical dimensions for the Pro models remain unchanged, so cases for iPhone 17 Pro models should fit the iPhone 18 Pro models.
Possible reasons: battery and cooling
Apple has not confirmed a single cause for the weight increase, but reports note two possibilities. The company may have enlarged the battery even though the external dimensions are identical, or the new vapor chamber cooling system may be heavier. The 18 Pro models feature a larger vapor chamber that occupies three times more surface area to dissipate heat.
Performance and battery impact
Apple says the A20 Pro can deliver up to 40 percent better sustained performance than the A19 Pro, attributed to the next-generation vapor chamber and “more thermally conductive materials.” Apple also states the 18 Pro Max battery provides up to six hours more video playback than the battery in the iPhone 17 Pro Max.
