How Much Do ‘Free’ Apps Really Cost?

Did you know that those free apps you are so addicted to are not exactly free? You pay a price one way or another. When researcher William Halfond from University of Southern California looked at this question closely, he came up with some stunning answers. His research showed that:

• Apps with ads use an average of 16 percent more energy, lowering the battery life of a smartphone from 2.5 to 2.1 hours on average — or down to 1.7 hours at the high end of energy usage.
• A phone’s Central Processing Unit (CPU) is like its brain, and ads eat up a lot of that brain power, slowing it down. Apps with ads take up an average of 48 percent more CPU time — 22 percent more memory use and 56 percent greater CPU utilization (the amount of time the CPU was used).
• Because the ads themselves are content that has to be downloaded, apps with ads cause smartphones to use much more data — up to 100 percent more, in some cases. On average, these apps use around 79 percent more network data, costing an estimated 1.7 cents every time they’re used (based on the average cost per MB charged by AT&T).

Halfond said, “In absolute terms, this is very low, but in the crowded and competitive world of apps it’s a huge difference. It can make the difference between your app getting downloaded or going unnoticed.” He is hoping app developers notice this research but admits that at the moment, they are kind of clueless.

The team compared 21 top apps from a list of 10,750, that had been in the top 400 of each of Google Play’s 30 categories, from January to August in 2014. They then measured their effect on phones with analysis tools loaded onto a Samsung Galaxy SII smartphone.

Halfond collaborated with  Meiyappan Nagappan of RIT, Stuart Mcilroy of Queen’s University, and Jiaping Gui of USC.

Written for the Ericsson blog.