Abstract: A method for ascertaining a Reynolds number compensated flow velocity and/or a Reynolds number compensated flow (G) by a Coriolis flow measuring device, comprising steps as follows: a. ascertaining at least one meter factor (C) during a calibration time interval in a calibration plant (a) based on measured values (A and B) of the Coriolis flow measuring device and a piston test apparatus of the calibration plant (a) by an evaluation unit of the calibration plant (a); b. transmitting the meter factor (C) from the evaluation unit of the calibration plant (a) to an evaluation unit of the Coriolis-flow measuring device; c. associating a Reynolds number (H) with this meter factor (D) while the Coriolis flow measuring device is connected to the calibration plant (a), and storing at least one data set of at least one number pair (D), in each case, of a Reynolds number and a meter factor, in the Coriolis flow measuring device; d.