A position determination device for determining and registering an injection location of administered fluid drug administration on a user, wherein the position determination device comprises - a position determination element adapted to determine a current location of the position determination device , the position determination element comprising at least one gyroscope and at least one accelerometer, and - one or more processing units adapted to derive data representing an actual injection location based on a current location determined by the position determination element , wherein the position determination device is adapted to - register a starting position in response to the user moving the position determination device to a pre-determined starting position, characterised in that the position determination device is further adapted to - register a location of an anchor position in response to the position determination element determining the movement from the starting position to the anchor position, - register a location of the actual injection location in response to the position determination element determining the movement from the anchor position to the injection location, - reset the position determination element to represent a starting movement vector at the starting position, - updating an internal representation of the position determination element to produce a three-dimensional movement vector in response to the distance moved from the starting position, - when the position determination device is moved to the anchor position then comparing the three-dimensional movement vector to calibrated vectors to determine which anchor position the position determination device is located at, and - determine an exact position of an injection site in response to the user moving the position determination element from the anchor position to a final injection site. - a position determination element adapted to determine a current location of the position determination device , the position determination element comprising at least one gyroscope and at least one accelerometer, and - one or more processing units adapted to derive data representing an actual injection location based on a current location determined by the position determination element , wherein the position determination device is adapted to - register a starting position in response to the user moving the position determination device to a pre-determined starting position, characterised in that the position determination device is further adapted to - register a location of an anchor position in response to the position determination element determining the movement from the starting position to the anchor position, - register a location of the actual injection location in response to the position determination element determining the movement from the anchor position to the injection location, - reset the position determination element to represent a starting movement vector at the starting position, - updating an internal representation of the position determination element to produce a three-dimensional movement vector in response to the distance moved from the starting position, - when the position determination device is moved to the anchor position then comparing the three-dimensional movement vector to calibrated vectors to determine which anchor position the position determination device is located at, and - determine an exact position of an injection site in response to the user moving the position determination element from the anchor position to a final injection site. <EOS>