This International Standard - specifies a method of determining the total emitted acoustic power of ultrasonic transducers based on the use of a radiation force balance; - establishes general principles for the use of radiation force balances in which an obstacle (target) intercepts the sound field to be measured; -establishes limitations of the radiation force method related to cavitation and temperature rise; - establishes quantitative limitations of the radiation force method in relation to diverging and focused beams; - provides information on assessment of overall measurement uncertainties. This International Standard is applicable to: - the measurement of ultrasonic power up to 1 W based on the use of a radiation force balance in the frequency range from 0,5 MHz to 25 MHz; - the measurement of ultrasonic power up to 20 W based on the use of a radiation force balance in the frequency range 0,75 MHz to 5 MHz; - the measurement of total ultrasonic power of transducers, preferably with well-collimated beams; - the use of radiation force balances of the gravimetric type or force feedback type.