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iPhone vs Samsung Battery Drain Test iPhone 1716 Pro Max iPhone Air Galaxy S25 Ultra S25 Edge
We ran the iPhone 17 and 16 Pro Max against the Galaxy S25 Ultra and S25 Edge in a real-world battery test. See which flagship survives the day.
Battery life remains one of the biggest priorities for UK smartphone buyers in 2026. As flagship devices continue to push performance, display brightness, and camera capabilities, the real challenge is delivering that power without constantly reaching for a charger.
At Zextons, our tech experts focus on how phones perform in real-world conditions rather than relying solely on laboratory figures. This detailed battery drain test compares Apple and Samsung’s most powerful premium smartphones to determine which device truly offers the best battery life during everyday use.
This comparison focuses on traditional flagship smartphones rather than foldables, which serve a different purpose entirely. Every phone tested sits at the very top end of the market, and interestingly, none of them include a charger in the box — a clear indication of just how premium these devices have become.
Phones Included in This Test
The test covers Apple and Samsung’s latest flagship models:
iPhone 17
iPhone 16 Pro Max
iPhone 17 Pro Max
iPhone Air
Samsung Galaxy S25 Ultra
Samsung Galaxy S25 Edge
Apple does not officially publish battery capacities, so the figures referenced are based on regulatory filings and trusted industry sources. While early data surfaced internationally, our UK-based analysis confirms these results hold true for the British market, with no meaningful battery hardware differences between regions.
Confirmed Battery Capacities (2025)
iPhone 17 Pro Max: 5,088 mAh
iPhone 16 Pro Max: 4,685 mAh
iPhone 17: 3,692 mAh
iPhone Air: 3,149 mAh
Galaxy S25 Ultra: 5,000 mAh
Galaxy S25 Edge: 3,900 mAh
On paper, the Galaxy S25 Ultra and iPhone 17 Pro Max sit at the top for capacity, while the iPhone Air clearly prioritises an ultra-thin design over outright endurance. As always, however, battery size alone does not determine real-world results.
How the Battery Drain Test Was Conducted
To ensure a fair and consistent comparison, all phones were tested under the same conditions:
Devices charged to 100%
Background activities disabled
Display brightness set to around 50%
Identical apps and tasks used on all phones
Real-world usage rather than controlled lab testing
This setup reflects how most users in the UK actually use their smartphones day to day.
Performance and Efficiency Observations
The test began with intensive performance benchmarks, including multiple runs of AnTuTu, Geekbench, and 3DMark.
The iPhone 17 Pro Max immediately stood out, scoring around 2.5 million points in AnTuTu, highlighting the sheer power of Apple’s A19 Pro chipset. Samsung’s Galaxy S25 Ultra and S25 Edge, powered by the Snapdragon 8 Elite for Galaxy, delivered strong flagship-level performance with no noticeable throttling, particularly in sustained GPU workloads.
One of the more surprising results came from the iPhone Air. Despite using the same A19 Pro chipset as the iPhone 17 Pro Max, its benchmark scores were noticeably lower. It appears the iPhone Air prioritises style over sustained sizzle, deliberately throttling performance to keep the ultra-thin frame from turning into a hand-warmer during extended workloads.
Even the regular iPhone 17, which uses a slightly downgraded A19 chip, delivered performance comparable to Samsung’s top devices, reinforcing just how far Apple’s efficiency gains have progressed.
Real-World Battery Drain Results
Heavy Performance Testing (First Hour)
After one hour of sustained benchmarking, the difference in efficiency became clear. Both Samsung phones dropped by around 18 percent, while the iPhone Air lost approximately 15 percent. The iPhone 17 Pro Max stood out by dropping just 11 percent, clearly demonstrating improved power management under load.
Video Streaming and Social Media
Extended YouTube Shorts playback further highlighted this gap. Samsung devices dropped to around 76 percent, while the iPhones — even models that were not brand new — retained noticeably more charge, sitting closer to 84–85 percent. Samsung’s displays looked excellent, particularly for HDR content, but this came at the cost of faster battery drain.
Video Calls and Mixed Usage
Google Meet was used to simulate real-world video calling, engaging the camera, microphone, and network simultaneously. After three hours of total use, the iPhone 17 Pro Max still had around 73 percent battery remaining. The Galaxy S25 Ultra sat at approximately 60 percent, while both the iPhone Air and Galaxy S25 Edge were at around 57 percent. Considering its small battery, the iPhone Air performed better than expected up to this point.
HDR Streaming and Media Consumption
HDR streaming on Netflix and YouTube told a similar story. The Galaxy S25 Ultra delivered a cinematic viewing experience, but its battery dropped faster than the competition. By comparison, the iPhone 17 Pro Max continued to hold a significant lead, maintaining well over 60 percent battery even after four hours of mixed media use.
Camera Stress Test and Heat Management
The most demanding part of the test involved one hour of continuous 4K 60fps selfie video recording. This is where the limitations of ultra-thin phones became clear. The iPhone Air lost around 40 percent battery in just one hour and reached temperatures of approximately 42°C, raising concerns about sustained camera use.
Larger phones handled this workload far better. The iPhone 17 Pro Max, iPhone 16 Pro Max, and Galaxy S25 Ultra all retained significantly more battery after the same test, highlighting the importance of thermal management in modern flagship devices.
Final Screen-On Time Results
Only three phones managed to cross the 8-hour screen-on time mark:
iPhone 16 Pro Max
iPhone 17
iPhone 17 Pro Max
Both Samsung models fell just short of eight hours, with the Galaxy S25 Edge and Galaxy S25 Ultra shutting down just under that mark.
The standout result came from the iPhone 17 Pro Max, which lasted an impressive 11 hours and 12 minutes of screen-on time. Even after crossing nine hours, it still had battery remaining — a clear indication of Apple’s efficiency gains this generation.
Charging Speed Comparison
Charging tells a more balanced story. In late 2026, Apple has finally become competitive here.
The iPhone 17, 17 Pro, and 17 Pro Max now support up to 40W fast charging, reaching around 50 percent in roughly 20 minutes. The iPhone Air, however, remains limited to 20W, reflecting its thinner design and thermal constraints.
Samsung still leads on raw charging speed, with the Galaxy S25 Ultra supporting 45W fast charging, while the S25 Edge sits lower. The iPhone 17 Pro Max does take longer to fully charge than Samsung’s flagships, but this is offset by its significantly longer battery life.
Battery & Charging Summary Table
Final Verdict from Zextons Tech Experts
From a real-world perspective, the results are clear. The iPhone 17 Pro Max sets a new benchmark for flagship battery life, combining outstanding performance with remarkable efficiency. Samsung’s Galaxy S25 Ultra and S25 Edge offer stunning displays and faster charging, but they simply cannot match Apple’s endurance this year. If endurance is your top priority, you can buy iPhones from our range, or shop Samsung flagships if you prefer a stunning display and faster charging.
The iPhone Air delivers respectable daily battery life for such a slim device, but heavy camera and video usage quickly expose its limitations. For UK users who prioritise long-lasting battery life above all else, the iPhone 17 Pro Max is currently the phone to beat. For more recommendations, see our guide to the best battery life phones in the UK.