This International Standard specifies the procedure of calibration of current-meters of rotating-element type as well as stationary-sensor type (electromagnetic type) in straight open tanks. It also specifies the types of tank, rating carriage and equipment to be used and the method of presenting the results. The procedure does not take into account any possible difference existing between the behaviour of a currentmeter moving in motionless water and that of a fixed current-meter in turbulent flow.