Update, 7 February 2017: We've replaced our previous pick, the Samsung Galaxy S7 edge, with a slightly larger and longer-lasting phone, the Huawei Mate 9.
Best overall
Huawei Mate 9
With a massive 5.9-inch display, you'd think that the Huawei Mate 9 wouldn't be able to last a whole day — but you'd be dead wrong. That screen is helped along by a 4,000mAh battery — one of the biggest in its class — pushing the Mate 9 to a staggering 2-day average uptime. Huawei's flagship device also has some Machine Learning chops that learn what apps you use most and least, in order to optimize them for battery usage.
Bottom line: A huge 4,000mAh cell plus software optimizations make the Huawei Mate 9 the best phone for battery life.
One more thing: Sometimes the Mate 9 can push battery optimizations a bit too far, so be sure to tweak your app settings when appropriate.
Why the Mate 9 is the best
An underrated performer in the U.S. because it doesn't have carrier support, but the Huawei Mate 9 is a serious worker.
Huawei has come a long way since its days of questionable software and China-only releases. The Mate 9 is now officially available in the U.S., and you get a lot with its $599 price tag, including a 4,000mAh battery that has to be one of the best out there. The company's homegrown Kirin 960 chip is not only fast, but its 16nm manufacturing process makes it extremely efficient.
Combined with the power-sipping 1080p LCD panel, the Mate 9 seemingly lasts forever; there wasn't a single day that reviewer Alex Dobie worried about it dying by the afternoon:
The phone never failed to get us through a full day of mixed use on LTE and Wi-Fi, often with more than 50% in the tank by the evening. Even pushing the phone really hard with lots of photography and a little wireless tethering, we never came close to experiencing battery anxiety.
Other than battery life, the Mate 9 is just an all-around great phone, and Huawei has committed to updating it with Alexa support in the coming months.
Best for sleekness
Samsung Galaxy S7 edge
See at AT&T See at Sprint See at T-Mobile See at Verizon See at Amazon
Battery life is subjective, of course, but having a bigger battery cell certainly helps. That, coupled with efficient software, is the recipe for all-day battery, and sometimes longer.
The Galaxy S7 edge has 3,600mAh cell that rivals much larger phones. It's amazing how slim and light the phone is considering how much juice they were able to fit into the device. Samsung also employs some software optimizations to ensure the phone keeps chugging along all day, too, including a very smart Power saving mode, and a last-resort Ultra power saving mode, which many other companies have since copied.
Bottom line: The Galaxy S7 edge does everything you want it to — speed, beauty, and camera quality — but if you're looking for all-day battery life, it's especially worth considering.
One More thing: This highly-rated device is available at all four major carriers in the U.S., but if you'd rather live dangerously and contract-free, Samsung offers an unlocked model that also works overseas.
Best for less
Moto Z Play
The Moto Z Play starts quickly and keeps going. It's actually quite amazing to witness. Thanks in part to the super-efficient Snapdragon 625 processor, which is built on a new 14nm process, the phone rarely gets hot, and with eight cores, works smarter, not harder.
With a 3,510mAh battery inside, along with software that feels as light as a feather, the Moto Z Play is the longest-lasting $400 phone we've used. It's also a pretty great smartphone, featuring a bright 5.5-inch display, a great 16MP camera, and support for Moto Mods.
Bottom-line: The Moto Z Play doesn't sacrifice much from its more expensive, much thinner Moto Z sibling. If you can deal with the added girth, and a slight hit to processing abilities, you get one of the best, longest-lasting Android phones around.
One more thing: Pair the Moto Z Play with Incipio's 2,220mAh OffGrid battery pack, and you have a whopping 5,730mAh combination that should last two full days, or longer!
Best for smaller hands
Honor 8
You wouldn't necessarily think of the Honor 8 as a phone with a long-lasting battery — it is quite a small device, after all — but Huawei, Honor's parent company, packed a 3,000mAh cell in there, along with a number of software optimizations to ensure it sips battery throughout the day.
Moreover, the Honor 8's Kirin 950 processor, built in-house by Huawei itself, finds the right balance between speed and efficiency. Couple that with the rest of the phone's excellent hardware — dual 12MP cameras, a bright, sharp 5.2-inch display, and plenty of storage — and you have a recipe for one of the best all-round Android phones on the market today.
Bottom-line: The Honor 8 is a great phone for anyone looking for at a smaller device without having to sacrifice battery life.
One more thing: You can buy the Honor 8 unlocked from a number of places, but Honor's website offers three months of screen protection warranty.
Conclusion
Most phones claim to have "all-day battery life," but few actually make it to bedtime. The Huawei Mate 9 actually backs up its claims, and does so while excelling in almost every other area.
Best overall
Huawei Mate 9
With a massive 5.9-inch display, you'd think that the Huawei Mate 9 wouldn't be able to last a whole day — but you'd be dead wrong. That screen is helped along by a 4,000mAh battery, one of the biggest in its class, pushing the Mate 9 to a staggering 2-day average uptime. Huawei's flagship device also has some Machine Learning chops that learn what apps you use most and least, in order to optimize them for battery usage.
Bottom line: A huge 4,000mAh cell plus software optimizations make the Huawei Mate 9 the best phone for battery life.
One more thing: Sometimes the Mate 9 can push battery optimizations a bit too far, so be sure to tweak your app settings when appropriate.