The portable ultrasonic flowmeter converters are paired with sensors in order to utilize the transit-time difference for measuring flow rates in pipes from the outside. It is a compact and lightweight instrument incorporating the latest electronics and digital signal processing technologies, realizing high performance and easy operation. This device is designed for high accuracy and high-speed response. This portable unit is capable of twelve-hours of continuous operation with its built-in battery, which requires only three hours to recharge. The rugged NEMA 3X enclosure allows the unit to be exposed to rain, while the efficient layout of the function keys aid the user with easy page selection and setting changes. The built in USB port allows for easy connection to a personal computer.