A compact ultrasonic flowmeter for measuring flowrate and other fluid related data of a fluid includes a flow tube with a flow bore for passage of the fluid between an inlet and an outlet, a flowmeter housing, a printed circuit board arranged in the flowmeter housing and including a processor for controlling operations of the flowmeter, a meter circuit including ultrasonic transducers provided on the printed circuit board and configured for operating the ultrasonic transducers to transmit and receive ultrasonic wave packets through the fluid, a display mounted on the printed circuit board and configured for displaying a measured flowrate and the other fluid related data, one or more battery packs for powering flowmeter operations, and two or more backing devices arranged to provide a holding force to the ultrasonic transducers, forcing a lower side of the ultrasonic transducers against transducer areas provided on the flow tube.