A filling level transmitter for measuring a filing level of a liquid includes: a filling level sensor having: an ultrasonic transceiver configured to emit ultrasound, and sensor electronics; a sound-conducting tube having two reflectors spaced apart from one another, the first reflector being configured to deflect ultrasound emitted by the transceiver in the direction of the second reflector, and the second reflector being configured to deflect the emitted ultrasound in the direction of the surface of the liquid. A third reflector is arranged in the second reflector such that emitted ultrasound impacting the third reflector is reflected in the direction of the first reflector.