iOS 26 Vs. iOS 18: Here's How Fast Liquid Glass Drains Battery Life

Apple rolled out the first commercial release of iOS 26 last week, bringing the new Liquid Glass user interface to millions of iPhone users. Liquid Glass was the most controversial aspect of iOS 26 during testing, and it generated similar reactions from users in the past few days. While there are ways to tone down the Liquid Glass transparency, users can't revert to the iOS 18 UI after upgrading to iOS 26. Apple rolled out the Liquid Glass design language to all its compatible products as well, not just the iPhone.

A few days after the release of iOS 26, YouTube channel In Depth Tech Reviews ran a test to determine whether iOS 26 consumes more battery life than iOS 18, and the results may give iPhone users another reason to dislike Liquid Glass beyond the transparency effects. It appears that the Liquid Glass animations require more processing power, which consumes more energy and generates more heat than the iOS 18 UI animations.

The YouTuber found that an iPhone 16 Pro Max running iOS 26 lost 13% of its battery life while performing the same actions as an iPhone 16 Pro Max on iOS 18. The latter consumed just 1% of battery during the test. Also, the iPhone running iOS 26 experienced higher temperatures than the one on iOS 18.

In Depth Tech Reviews first ran the experiment in July, comparing an iOS 26 beta release to a stable iOS 18.5 version. He repeated the same test last week, after iOS 26 officially launched. The YouTuber used similar testing conditions. Each iPhone 16 Pro Max runs a stable version of iOS, the battery charge is set at 80%, and the screen brightness is set at 50%. Also, each iPhone is connected to Wi-Fi and lacks a SIM card.

To simulate real-life usage, the YouTuber performed four actions manually. He pulled down the Notification Center, he opened and closed apps (Safari), he scrolled in apps (Photos), and he unlocked the iPhone. Each action was repeated 150 times, which is the average number of times a smartphone user picks up their phone a day. As you can see in the clip above, each action led to considerable battery drain on iOS 26 compared to iOS 18. The iPhone 16 Pro Max running iOS 26 heated up significantly for each task, suggesting that the Liquid Glass animations are more resource-intensive.

This isn't a purely scientific test. The YouTuber tested iOS 26 in September and iOS 18 in July, rather than performing the test side-by-side. It's unclear whether he controlled the ambient setting, such as the temperature of the room. Also, the YouTuber used transparent icons in iOS 26 rather than the default ones. However, the results are still relevant, as they're consistent with the July findings. These tests indicate Liquid Glass may be more resource-intensive than iOS 18, something Apple implied on stage at WWDC 2025.

"Now, with the powerful advances in our hardware, silicon, and graphics technologies, we have the opportunity to lay the foundation for the next chapter of our software," Apple's vice president of Human Interface, Alan Dye, said before introducing Liquid Glass. Apple did not address battery concerns related to Liquid Glass at the time.

However, Apple released a support document last week to address battery life concerns related to the iOS 26 update, warning that users might experience "a temporary impact on battery life and thermal performance" after performing an update to a major release. Apple said that behavior is normal. The company did not link temporary battery drain to Liquid Glass, but said that "some [features] may require additional resources from the device," and said that some users "may notice a small impact on performance and/or battery life."