RFID reader and method for recognizing RFID tags

The invention refers to an RFID reader (1) comprising a transmitter (2), a receiver (3), and an evaluator (4). The receiver (3) receives signals from RFID tags (10) within a given number of slots of a time frame with a given frame size (L) and provides a number of successful slots (ss) and a number of collided slots (cs). The evaluator (4) sets a modified frame size (L') based on an estimated number of RFID tags (n est ) which is determined based on the frame size (L), the number of successful slots (ss), and the number of collided slots (cs). The invention also refers to a corresponding method.