Technologies are generally described for distance determination between two or more RFID tags based on a minimum detectable signal. In some examples, a first RFID tag may establish communication with a second RFID tag, and modulate an irradiating electromagnetic field to generate backscatter signals for sequential transmission to the second RFID tag. A depth of amplitude modulation of each transmitted signal may be progressively reduced until the second RFID tag can no longer detect the modulation. The particular distance between the first and second RFID tags may then be determined based on a minimum detectable signal by the second RFID tag, which may be identified as a last transmitted signal detected by the second RFID tag. In some embodiments, distance determination between two or more RFID tags as described above may be implemented for robotic sensing, assembly systems, security, and wearable technology to track motion and/or position of objects.