A clamp-on ultrasonic flowmeter includes a measuring tube, a pair of ultrasonic contact transducers, and an electronic measuring/operating circuit for operating the transducers. Each transducer includes a transducer element for generating and detecting ultrasonic signals and a coupling element. The transducer element is located on one side of the coupling element facing away from the measuring tube, and is designed to be acoustically coupled to the measuring tube via another side of the coupling element facing the measuring tube, and designed to transmit ultrasonic signals between the transducer element and measuring tube. The ultrasonic flowmeter comprises an adjusting device for at least one transducer for adjusting the transducer. The adjusting device is arranged and configured to modify at least one angle of the signal path with respect to the coupling face or a signal path length, wherein the adjusting device has at least two degrees of freedom.