According to one embodiment, an apparatus for selecting a battery voltage table including current consumption information of applications, and applying an offset to a battery output voltage according to current consumption of applications. The apparatus for determining a battery status in a portable terminal includes a memory unit configured to store a battery voltage table defined according to current consumption, a control unit configured to determine an executed application, and a power estimation unit configured to estimate a battery level using the battery voltage table defined for each current consumption of applications and a battery output voltage.