I’m definitely not the first to consider this nagging question—as evidenced by threads on Quora, Reddit, and Yahoo Answers—but i wanted to independently test this hypothesis so I could be absolutely sure it’s true. So, I charged my iPhone 5 completely and kept it in airplane mode with all apps besides Music closed and the screen off. Then I let the music play.
For music I picked Speedy Ortiz’s Major Arcana and let it loop over and over through crummy EarPods under a pile of socks to muffle the noise. Early estimates suggested it would have taken several days to drain my poor old phone’s battery from 100 percent to nothing, so I capped each test after 5 hours.
After playing music on one bar of volume for five hours, my battery was knocked down to 92 percent. When i tried the same test at full volume, it resulted in... an 89 percent charge. Pretty small difference. Judging by these (barely scientific) results, every added bar of volume will kill a whopping 0.001875 percent of your phone’s battery after playing a three-minute song.
For comparison, I left my phone’s display on with all apps closed and the phone set to airplane mode. After five hours, the battery was brought down to 73 percent charge. And that was without any music playing. So it’s safe to say your display will deplete your battery much faster than playing music ever will.
Some people suggested that headphones with more impedance or larger drivers might have a more pronounced effect on battery usage, but I didn’t find that to be the case. I ran the same test on a pair of Seinnheiser HD 280 Pros that run at an estimated 45 ohms (as opposed to 64 ohm for the 280s). Five hours of full-volume-blasting Speedy Ortiz later and the Sennys had puzzlingly brought the battery down to 90 percent.
How these massive DJ headphones were more efficient than tiny little earbuds will forever remain a mystery. I considered testing some of the 600 ohm headphones on the market, but decided that few people, if any, are actually dragging those and the matching headphone amp around with them. So I decided our test was finally complete.
Did I spend 20-plus hours acquiring the least useful piece of battery life trivia? Yes and no. The exact number is less important than knowing that, in a pinch, quieter music will, surprisingly, squeeze a little more time out of your near-dead phone. Flip on airplane mode, kill the display, and you just might have a soundtrack for your drunken walk home.