Which phone has the longest battery life? Galaxy S24 Ultra vs iPhone 15 Pro Max vs OnePlus 12 vs Pixel 8 Pro

S24 Ultra, iPhone 15 Pro Max, Pixel 8 Pro, and OnePlus 12.
(Image credit: Future)

What an amazing season it’s been in the flagship phone race. It starts in the early fall with releases like the iPhone 15 Pro Max and Pixel 8 Pro, then it carries over into the new year with the Galaxy S24 Ultra and OnePlus 12. Now that all the major phone makers have released their flagship models, we’re able to properly test them to know which one can top our best phone battery life list.

In order to earn a seat, these flagships will have to exceed the 10 hours of battery life that most phones average on our custom battery benchmark test. How do we test smartphone battery life? This is done by using a light meter to calibrate their displays to 150 nits, then running a script that simulates web surfing over 5G cellular connectivity. This is done until their batteries are depleted.

Battery life improvement has typically been iterative, usually beating their predecessors by an hour. However, this graduating class took greater leaps to push beyond that one-hour battery life improvement. In this Galaxy S24 Ultra vs iPhone 15 Pro Max vs OnePlus 12 vs Pixel 8 Pro battery life showdown, we’ll dial into how long they last to ultimately crown a winner — along with how fast they charge.

Flagship phone battery life tested

Swipe to scroll horizontally
PhoneBattery sizeBattery test result (Hrs Mins)
OnePlus 125,400 mAh17:41
Galaxy S24 Ultra5,000 mAh16:45
iPhone 15 Pro Max4,422 mAh14:02
Pixel 8 Pro5,050 mAh10:03

Starting off with the one with the shortest battery life, the Pixel 8 Pro lands in last position with a time of 10 hours and 3 minutes. It technically has the third largest battery capacity, but it seems that the Tensor G3 is the least power efficient of the bunch. Despite offering the shortest battery life amongst this flagship group, it’s an improvement over its predecessor’s subpar 7 hours and 55 minutes. When we look at it from this perspective, it’s still a significant improvement for Google.

Coming in third place is the iPhone 15 Pro Max, reaching 14 hours and 2 minutes in our benchmark testing. Apple’s newest silicon, the A17 Pro, makes substantial gains in the processing department, which also contributes to the phone’s improved battery life. The previous iPhone 14 Pro Max reached a time of 13 hours and 39 minutes before tapping out.

Our runner up in this battery life showdown goes to the Galaxy S24 Ultra and its beefy 5,000 mAh battery. What’s impressive here is that the battery capacity isn’t as big as the Pixel 8 Pro, which means its endurance is the result of the outstanding power efficiency of its chipset — the Snapdragon 8 Gen 3 — leading to a time of 16 hours and 45 minutes. Samsung’s newest flagship easily eclipses the iPhone 15 Pro Max by almost 3 full hours, as well as its predecessor by over 3.5 hours.

OnePlus 12 held in the hand.

(Image credit: Future)

Qualcomm deserves its fair share of adulation because its Snapdragon 8 Gen 3 propels our top winner to new heights. The OnePlus 12 is the unanimous champion in this battery endurance test with its unbelievable time of 17 hours and 41 minutes.

Sure, we could thank its 5,400 mAh battery for its extra long-lasting time, but it has a lot more due to how much more power efficient the Snapdragon 8 Gen 3 is against the other chipsets. Even more remarkable is that the OnePlus 12 beats its predecessor in the OnePlus 11 by about 4.5 hours, which says a lot about the leap in battery life we’re seeing this time around.

If things stay on course, we could very well see the next batch of best phones reach closer to the 20 hour mark on our battery benchmark test. While the battery tech behind today’s phones hasn't seen a tremendous change, a lot of the improvements we're seeing here is due to the optimizations of these chips.

Flagship phone battery recharge tested 

Swipe to scroll horizontally
PhoneRecharge percentage (15 mins)Recharge percentage (30 mins)
OnePlus 1260%100%
Galaxy S24 Ultra39%71%
iPhone 15 Pro Max20%41%
Pixel 8 Pro29%59%

Having more gas in the tank is undoubtedly helpful, but so is having a phone that can recharge quickly. Thankfully, many flagships employ their own rapid charging tech to get their battery capacities to a decent level with a short charge.

Even though a lot of people were happy to see Apple adopting USB-C, the iPhone 15 Pro Max still takes a long time to charge. In fact, it manages to get to 41% with 30 minutes of charging. That’s because of its slower 20W wired charging speed, which is glacial in the world of flagships.

Next up on the recharge list is the Google Pixel 8 Pro, which reaches to a better capacity of 59% in 30 minutes of charging. That’s not too shabby given that it benefits from a slightly faster 30W wired charging speed.

Pixel 8 Pro and iPhone 15 Pro Max next to one another.

(Image credit: Future)

Just as before, the Galaxy S24 Ultra takes the runner up position in our battery recharge test by reaching a commendable 71% in 30 minutes. It’s able to achieve this because of its faster 45W wired charging speed, and that’s despite being unchanged over its predecessor. If you’re strapped for time, we also find its 39% charge level with 15 minutes of charging respectable for when you need to top up.

And finally, there’s the OnePlus 12 with its obscene 80W wired charging that fills up the phone to 100% in 30 minutes. It demolishes all the other flagships here, but equally impressive is its charge level of 60% with 15 minutes of charging. OnePlus certainly makes battery and charging its priority because other recent releases, like the OnePlus Open and 12R, also achieve impressive results.

OnePlus also deserves recognition for being one of the few phone makers to include a charging adapter with its phones. The OnePlus 12, for example, comes with an 80W charging adapter — whereas the other phones require you to purchase them separately.

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John Velasco
Senior Channel Editor for Phones

John’s a senior editor covering phones for Tom’s Guide. He’s no stranger in this area having covered mobile phones and gadgets since 2008 when he started his career. On top of his editor duties, he’s a seasoned videographer being in front and behind the camera producing YouTube videos. Previously, he held editor roles with PhoneArena, Android Authority, Digital Trends, and SPY. Outside of tech, he enjoys producing mini documentaries and fun social clips for small businesses, enjoying the beach life at the Jersey Shore, and recently becoming a first time homeowner.