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.