Quick Answer
The iPhone 18 Pro Max finished first overall in CNET’s 32-phone battery test, while the iPhone Duo tied for fourth. Both ended the 45-minute mixed-use test at 99%, sharing first place in that round.
The three-hour Wi-Fi streaming test separated them. The Pro Max finished at 92%, the Duo at 84%, and the smaller iPhone 18 Pro led the round at 94%.
That makes the streaming result more informative for long video sessions. The mixed-use tie tells you how the phones handled one short session from a full charge. CNET ranked the phones by averaging the two end-of-test readings. See MacRumors’ recap and the published chart figures.
45 minutes of mixed use: A tie at 99%
CNET started each phone at 100% and cycled through video, a video call, gaming and social media. Both phones showed a one-percentage-point drop. The battery meters showed no meaningful separation over a short burst of activity.
Each of CNET’s two tests started at full charge. Projecting that first 1% drop across a full day would assume the battery drains at the same pace through every task and at every charge level. See 9to5Mac’s breakdown of the test method.
Three hours of streaming: Where the gap opened
CNET streamed video over Wi-Fi for three hours at maximum screen brightness. The Pro Max kept eight percentage points more charge than the Duo. The 6.3-inch iPhone 18 Pro finished two points ahead of the Pro Max, leading all 32 phones in this round. The figures below are percentages of battery remaining.
| iPhone | 45 min mixed |
3 hr streaming |
Overall rank |
|---|---|---|---|
| 18 Pro Max | 99% | 92% | 1st |
| 18 Pro | 93% | 94% | Tied 2nd |
| Duo | 99% | 84% | Tied 4th |
Each test contributed equally to the ranking, even though streaming ran four times as long. The Pro Max averaged 95.5%, the 18 Pro 93.5%, and the Duo 91.5%. The Duo shared its ranking with the iPhone 17e and Motorola Razr Ultra (2026). See CNET’s original test and iClarified’s reproduction of the overall rankings.
What the test tells you about everyday battery life
Several episodes on Wi-Fi
The streaming round is the closer match, especially if you watch with the brightness turned up. CNET’s result gives the Pro Max the edge over the Duo for that kind of session.
A day away from a charger
A commute with cellular navigation, time spent outdoors and hours of standby add different demands. If that sounds like your day, the overall ranking gives you a starting point. The test leaves the size of the gap on your own schedule open.
Does the Duo’s outer screen change the comparison?
Apple’s U.S. specs list up to 37 hours of streamed video on the Duo’s outer display and 26 hours on its inner display. Apple rates the iPhone 18 Pro Max at up to 40 hours and the smaller iPhone 18 Pro at up to 33 hours under its own streaming protocol. See the iPhone Duo specs, iPhone 18 Pro and Pro Max specs and Apple’s battery test details.
The published summaries leave the Duo’s display configuration unspecified, so its 84% finish can’t tell you how the outer and inner screens compare in CNET’s setup. If you spend much of the day using the Duo folded, Apple’s two separate ratings are useful context. See our closer look at Duo display use and battery drain.
Filming is a different battery workload
CNET’s three-hour round measures watching video. For continuous filming, Mediastorm ran a separate two-hour test in which the Duo finished at 61% and the Pro Max at 59%. Read ZEERA’s breakdown of the Mediastorm recording and playback tests.
The broader buying comparison is drawing attention too. 9to5Mac’s November 10 video about choosing the Duo over the smaller iPhone 18 Pro reached roughly 207,000 views in about two days. Watch 9to5Mac’s iPhone Duo vs. iPhone 18 Pro video.
Related Reading
- iPhone Duo Review Hub: Specs, Problems and Test Results
- iPhone Duo vs. iPhone 18 Pro Max: Heat, Performance and 5G
- iPhone Duo Charging Speed: USB-C vs. MagSafe
- Keep the iPhone Duo or Switch to the iPhone 18 Pro Max?
FAQ
Which iPhone lasted longer while gaming?
Gaming was one part of the 45-minute mixed run. You’d need a dedicated session using the same game, graphics settings and brightness to see which phone drains more slowly while gaming.
How does the Duo’s 51.5-hour EU battery rating fit in?
The EU energy label reports endurance under a standardized usage cycle. It answers a different question from CNET’s remaining-charge snapshots. For the rating and the Duo’s 4,883 mAh capacity, see our iPhone Duo EU battery label explainer.
