For most people, the iPhone 18 Pro Max is the better buy. It costs $700 less, has the more capable camera and lasts longer on a charge. The iPhone Duo is worth its $1,999 price if you want a screen big enough to work on like a small tablet that still folds down to fit in a pocket.
The two have more in common than the price gap suggests. Both run on Apple's A20 Pro chip, both are rated IP68 and both come with 256GB to 2TB of storage. I tested the 18 Pro Max's camera for our hands-on in October, but we haven't had a Duo in hand yet, so the Duo figures below come from Apple's own pages.
The Duo's main draw is a much bigger screen
Open, the Duo has a 7.6-inch inner display, which Apple says is 50 percent larger than the 18 Pro Max's 6.9-inch screen. That leaves room for two apps side by side, and Split View on the Duo is the first time Apple has offered it on an iPhone. Closed, the 5.4-inch outer display has about 90 percent of the screen area of the smaller iPhone 18 Pro, so quick replies and maps don't need the phone opened.
Both displays on the Duo use ProMotion up to 120Hz and reach 3,000 nits outdoors, the same as the 18 Pro Max. The inner screen also has a matte nano-texture finish to cut glare. When it announced the Duo in September, Apple said Apple Pencil (USB-C) support would come later this year.
Both phones share the same chip and water rating
The A20 Pro powers both phones, and both are rated IP68 for up to 6 meters of water for 30 minutes. The Duo is eSIM only worldwide, the US 18 Pro Max is eSIM only too, and both support Wi-Fi 7. In the Duo, Apple pairs the chip with a custom vapor chamber and says it delivers up to 35 percent better sustained performance than the iPhone 17 Pro. Its announcement compares the Duo with the 17 Pro, not with the 18 Pro Max.
The 18 Pro Max has the stronger camera
The 18 Pro Max has three 48MP rear cameras: a main camera with a variable aperture from f/1.48 to f/4, an ultra wide and a 4x telephoto that also gives an optical-quality 8x. Digital zoom goes up to 40x, and it records ProRAW photos and ProRes video. The Duo has two 48MP rear cameras, a main camera with a fixed f/1.6 aperture and an optical-quality 2x crop, plus the same ultra wide as the 18 Pro models. Its digital zoom stops at 10x, and Apple's Duo spec page doesn't list ProRAW or ProRes.
The variable aperture was the change that showed most in my own photos. On a close-up of a car badge, moving from f/1.48 to f/4 brought the paint in front of the badge into focus, and our variable aperture test has the full set.
The Duo makes up for some of that with tricks the fold allows. You can take a selfie with the rear cameras and see the preview on the outer display, Smart Take can snap a photo on its own when your subjects are posing, and you can prop the phone up for time-lapses without a tripod.
The 18 Pro Max lasts longer between charges
Apple rates the 18 Pro Max for up to 30 hours of typical use and 45 hours of video playback. The Duo gets up to 24 hours of typical use when both displays are used equally, and up to 31 hours of video on the inner display or 44 hours on the outer one. With a compatible USB-C power adapter of 60W or more, Apple says the 18 Pro Max reaches 50 percent in around 15 minutes and the Duo in around 20 minutes. Both charge wirelessly at up to 25W with MagSafe or Qi2.
Size, weight and unlocking are different
Closed, the Duo is 117.8mm tall, 84.1mm wide and 11.3mm thick, so it is much shorter than the 18 Pro Max, at 163.4mm tall, but wider and thicker than its 78mm by 8.75mm. Opened flat, the Duo is 5.2mm thick. The two weigh almost the same, at 254 grams for the Duo and 249 grams for the 18 Pro Max.
The Duo unlocks with Touch ID in the side button, open or closed, while the 18 Pro Max uses Face ID. The Duo has a mirror-polished titanium body in star white or night sky. The 18 Pro Max has an aluminum body in black, silver, glacier or burgundy.
Which one should you buy
Pick the iPhone 18 Pro Max if the camera matters most, especially zoom, or if you want the longer battery life and $700 back in your pocket. It starts at $1,299, or $54.12 a month for 24 months in the US. Pick the iPhone Duo if you read, watch video or juggle two apps on your phone every day, and you'd rather carry one folding phone than a phone and a small tablet. It starts at $1,999, or $83.29 a month for 24 months.
For more on each phone, see our iPhone 18 Pro Max hands-on and our coverage of the iPhone Duo launch.
