Summer’s in full, lazy swing now. But as you think about catching some rays, you may want to know — how long can I really stay out in the sun? Suntime, an app for the iPhone, iPod Touch and iPad, aims to answer that question. Users select their skin type, SPF factor and UV index to calculate the perfect amount of time in the sun. They can also add in other factors such as altitude.

The app is admittedly a bit complicated to set up. Few people know off the tops of their (hat-covered) heads what the UV index is on a given day, and calculating your altitude in meters is not exactly a natural activity while sunbathing. The app also isn’t optimized for kids, who have more sensitive skin. So while Suntime is a useful app, users should know that it isn’t a breeze to use. Then again, watching your health never is. $1.99, for iOS devices.

— Hayley Tsukayama