Disclosed are a device, computer program and method, for determining a range to a target, the device comprising a global positioning system (GPS) receiver, a pressure sensor, a temperature sensor, a controller; wherein the method comprises determining the device's geographic location based on coordinates from the GPS receiver and the device's elevation based on pressure and temperature data from the sensors; obtaining a location and elevation of a landmark based on GPS coordinates from a database; determining a distance between the device and the landmark using GPS coordinates; applying a slope compensation based on the difference in elevation between the device's elevation and the landmark; and converting the distance to a signal perceptible to a user.