The OnePlus 15 is one of the best flagships in terms of battery life that we've tested.
In the ongoing contest between flagship Android devices, OnePlus and Samsung have each staked a claim to the premium tier with the OnePlus 15 and Galaxy S25 Ultra — two phones that share a processor and a price bracket but diverge sharply in their philosophies of endurance versus refinement. The comparison, conducted in late 2025, reveals that technological parity at the top of the market does not mean interchangeability: the choices embedded in each device reflect different answers to the question of what a phone is fundamentally for. One prioritizes the freedom of lasting longer between tethers; the other, the precision of a sharper, more polished experience.
- The OnePlus 15 arrives with a 7,300mAh battery — nearly half again as large as the Galaxy S25 Ultra's 5,000mAh cell — and in testing it delivers over seven hours of screen-on time before the Samsung has even reached its final quarter.
- Charging speed deepens the gap: OnePlus reaches a full charge in 40 minutes with a charger included in the box, while Samsung takes over an hour and ships without one.
- Both phones run the same Snapdragon 8 Elite chip, but OnePlus pairs it with faster RAM, higher storage throughput, and a 165Hz gaming refresh rate that Samsung's adaptive 120Hz panel cannot match.
- Samsung counters with a sharper 3120x1440 display, superior glare resistance through Gorilla Glass Armor 2, and a 200-megapixel main camera that dwarfs OnePlus's three 50-megapixel sensors — though neither phone ranks among the market's best for photography.
- The decision resolves not into a winner but into a mirror: buyers must ask whether they value the liberation of endurance or the precision of Samsung's more polished, if less tireless, ecosystem.
OnePlus has brought its latest flagship to global markets with a direct challenge to Samsung's Galaxy S25 Ultra — and the comparison that follows is less a verdict than a study in divergent priorities.
Both phones are large, premium, and built from quality materials, but they differ in feel. The OnePlus 15 uses aluminum with gentler curves and is fractionally lighter; the Galaxy S25 Ultra wraps itself in titanium with sharper edges. OnePlus earns a tougher IP68/IP69K water resistance rating; Samsung stops at IP68. Their displays are similarly excellent but differently tuned — OnePlus offers higher peak brightness and superior PWM dimming at 6.78 inches, while Samsung's 6.9-inch panel is sharper and handles glare more gracefully.
Under the hood, both phones run Qualcomm's Snapdragon 8 Elite, though OnePlus pairs it with faster RAM and storage, and measurably outperforms Samsung in benchmarks — a gap that remains invisible in daily use but surfaces in sustained gaming sessions where OnePlus also offers better thermal management and higher refresh rates.
The most decisive separation is in battery and charging. The OnePlus 15's 7,300mAh silicon-carbon cell is in a different category from Samsung's 5,000mAh offering, and in testing it proved it — delivering over seven hours of screen-on time while the Galaxy S25 Ultra was approaching its final quarter. OnePlus also charges to full in 40 minutes at 120W and ships with a charger; Samsung takes over an hour at 45W and does not.
Cameras offer a more complicated picture. OnePlus fields three 50-megapixel sensors including a periscope telephoto; Samsung answers with a 200-megapixel main camera and four lenses total. In practice, they trade strengths by scene, and neither ranks among the market's finest for photography. Both offer stereo speakers and USB-C, with no headphone jack on either.
The conclusion is honest rather than decisive: if battery life and charging speed are your priorities, the OnePlus 15 wins clearly. If a sharper display and Samsung's ecosystem matter more, the Galaxy S25 Ultra remains a formidable choice. Neither is a mistake.
OnePlus has brought its latest flagship, the OnePlus 15, to global markets, and it arrives with a direct challenge to Samsung's reigning top-tier device: the Galaxy S25 Ultra. Both are large-format phones built from premium materials, but they diverge in meaningful ways—ways that matter if you're actually trying to decide which one to carry.
Start with what you'll hold. The Galaxy S25 Ultra wraps its frame in titanium and cuts sharper corners; the OnePlus 15 uses aluminum and curves more gently. The OnePlus is fractionally smaller and lighter, though the difference barely registers. The OnePlus puts a multifunctional button on the left side where Samsung's alert slider used to live, while Samsung consolidates all physical controls to the right. On the back, the OnePlus camera module sits as a rounded square in the top-left corner, housing three lenses. Samsung's four cameras protrude directly from the backplate. Both phones are slippery enough that you'll want a case. The OnePlus carries a tougher IP68/IP69K rating against dust and water; Samsung stops at IP68.
Their displays tell a similar story of excellence with different strengths. The OnePlus 15 offers a 6.78-inch LTPO AMOLED panel that reaches up to 165Hz refresh rate during gaming and achieves a peak brightness that technically surpasses Samsung's offering. It supports Dolby Vision and HDR10+, and its high-frequency PWM dimming is notably superior for reducing flicker. The Galaxy S25 Ultra counters with a 6.9-inch Dynamic LTPO AMOLED 2X display running at 1-120Hz adaptive refresh, a sharper 3120 x 1440 resolution, and Gorilla Glass Armor 2 that handles glare better. Both are vivid, smooth, and bright enough for outdoor use. For most viewers, the difference is academic.
Under the hood, both phones run Qualcomm's Snapdragon 8 Elite processors—the OnePlus with the Gen 5 variant paired with up to 16GB of LPDDR5X RAM and UFS 4.1 storage, Samsung with its Galaxy-specific version, 12GB of RAM, and UFS 4.0. The OnePlus is measurably faster in direct comparison, though both are so fluid in daily use that you won't notice the gap. For gaming, the OnePlus leans harder into the category with better thermal management, higher refresh rates for certain titles, and more elaborate gaming software. Neither phone overheats during intense sessions. Storage expansion is unavailable on either device.
Battery life is where the OnePlus pulls decisively ahead. Its 7,300mAh silicon-carbon battery dwarfs the Galaxy S25 Ultra's 5,000mAh cell—a gap that widens when you account for the fact that Samsung's phone has a slightly larger display. In testing, the OnePlus 15 delivered over seven hours of screen-on time before dropping to 50 percent battery. The Galaxy S25 Ultra would be in its final quarter by that point. Both phones will satisfy most users, but if longevity between charges matters to you, the OnePlus is the stronger choice.
Charging speed amplifies that advantage. The OnePlus 15 supports 120W wired charging (80W in the US), 50W wireless, and 10W reverse wireless. It reaches a full charge in 40 minutes and ships with a charger in the box. The Galaxy S25 Ultra maxes out at 45W wired, 15W wireless, and 4.5W reverse wireless, requiring an hour to fully charge with a compatible charger—and Samsung doesn't include one. The OnePlus also supports Bluetooth 6.0 versus Samsung's Bluetooth 5.4.
Cameras present a more nuanced picture. The OnePlus 15 fields three 50-megapixel sensors: a main camera with a 1/1.56-inch sensor, a 116-degree ultrawide, and a 3.5x optical zoom periscope telephoto. The Galaxy S25 Ultra brings a 200-megapixel main camera, a 50-megapixel ultrawide, a 10-megapixel 3x telephoto, and a 50-megapixel 5x periscope telephoto. In practice, they trade strengths depending on the scene. Samsung's main camera tends toward warmer tones; the OnePlus renders differently. Neither ranks among the market's best camera phones. Both ultrawide cameras lag behind their main shooters, and the OnePlus's telephoto results edge out Samsung's, though Samsung performs capably. For audio, both offer stereo speakers with similar loudness and quality, and both ditch the headphone jack in favor of USB-C connectivity.
The choice between them hinges on priorities. If battery endurance and charging speed matter most, the OnePlus 15 is the clearer winner. If you value a sharper display and prefer Samsung's ecosystem, the Galaxy S25 Ultra remains a formidable flagship. Neither is a mistake.
Notable Quotes
After slightly over 7 hours of screen-on-time with the OnePlus 15, we were left with half the battery tank left. The Galaxy S25 Ultra would be in its last quarter at that point, at best.— Android Headlines review testing
The OnePlus 15 is a bit more oriented towards gaming. It comes with better cooling, provides a higher refresh rate for some games, and it has a more elaborate gaming software.— Android Headlines comparison
The Hearth Conversation Another angle on the story
Why does the OnePlus 15 last so much longer on a single charge?
It's the battery itself—7,300 milliamps versus 5,000. That's a 46 percent larger capacity. But it's not just raw size. The OnePlus also runs more efficiently. Samsung's display is slightly bigger, which works against battery life. Over seven hours of actual screen-on time, the OnePlus still has half its tank left.
That's a significant gap. Does it matter in real life, or is this a spec-sheet victory?
It matters. Most people will get through a full day with either phone, sure. But if you travel, if you're away from a charger for extended periods, or if you simply don't want to think about battery anxiety—the OnePlus wins. It's not marginal.
What about the cameras? The Galaxy S25 Ultra has a 200-megapixel main sensor. Shouldn't that be better?
Megapixels are misleading. The OnePlus uses a smaller sensor with three 50-megapixel cameras instead. In actual shooting, they trade wins depending on light and subject. Neither is best-in-class. Samsung leans warmer, OnePlus is different. You're not choosing between a great camera and a mediocre one—you're choosing between two good ones with different personalities.
The OnePlus charges in 40 minutes. The Galaxy takes an hour. Is that a real difference or marketing?
It's real. Forty minutes versus sixty is meaningful if you're in a hurry. But here's the kicker: Samsung doesn't include a charger in the box. OnePlus does. That's a practical advantage that compounds the speed difference.
Both phones are expensive. What would make someone choose Samsung despite these OnePlus advantages?
The display is sharper, the titanium frame feels more premium, and Samsung's ecosystem integration is tighter if you own other Samsung devices. The Galaxy S25 Ultra is still an excellent phone. It's just that the OnePlus 15 is better at the things that affect daily life—how long you go between charges, how fast you can top up, how the phone feels in your hand.