Macworld

The always-on display is a brilliant feature, particularly on the Apple Watch, where it makes the smartwatch look just like a proper watch. With the iPhone 14 Pro, Apple began incorporating a similar technology into the iPhone. Starting with the iPhone 17, Apple included the always-on display on all models except the iPhone 17e.

But how does the always-on display affect an iPhone’s battery life? After all, the battery has to power the large screen almost constantly. There are situations where the always-on display is switched off, despite the setting being enabled: in Sleep mode, when the iPhone is lying face down, when a paired Apple Watch isn’t nearby, or when CarPlay is activated in the car.

I ran a few tests to compare battery life when the always-on display is activated, and compared the results to when the display turns off when it’s not in use. Surprisingly, the results aren’t as drastic as one might think.

Testing battery life

My two weeks of testing involved an iPhone 17 running iOS 27 Beta 3. In the first week, I used the iPhone daily with the always-on display. In the following week, the screen was switched off. From the recorded data, I extracted the battery statuses at 15-minute intervals for each day and categorized them as Always On and Always Off. This yielded 672 data points in each category.

Effect of always-on display on the iPhone battery

Foundry

If you filter out the rows in both datasets showing the battery level when the iPhone was being charged, and calculate the discharge rate per hour, it turns out that the iPhone discharges at an average rate of 4.27 percent per hour when the display is always on. For an iPhone with the display deactivated, this rate is 3.75 percent per hour. The discharge rate during the day, from 8 a.m to 11 p.m., was 5.88 percent with the always-on display activated, and 5.37 percent with it off.

As can be seen from the data in the graph above, both discharge curves run almost parallel. There are no major discrepancies between the different settings that would suggest the always-on display being switched off has a significant effect on battery life. The t-test, which precisely calculates the significance of a factor, also yields a p-value of 0.3011 in this case. Significance is established at a p-value of 0.05 or less. This means that whether the always-on display is enabled or disabled has no significant effect on battery life.

Our measurement data supports what Apple claimed when introducing the always-on display in 2022. When the screen is locked, it is throttled down to 1Hz, which reduces power consumption. In the chaos of everyday life, which is influenced by user behavior, signal strength, and outside temperatures, whether the screen is on or off does not make a significant difference.