Which? tested laptops for battery life while actively browsing the web over Wi-Fi, running the laptops in this fashion until the battery was fully drained. The number of laptops tested: Acer (8); Apple (3), Asus (8), Dell (10), HP (12), Lenovo (20), Toshiba (6).
Which? says, for example, that Apple's claimed battery life for the 13-inch MacBook Pro is 12 hours; the testing site tallied 12 hours.