Determination of acoustic phase velocity in liquid or solid specimens using standing‐wave (i.e., continuous wave) ultrasonic techniques requires the use of a transducer correction formula. Previous approximations for the transducer correction in the case of a one‐dimensional (planar) composite resonator are considered explicitly and their accuracy and range of validity are quantitatively examined. An improved transducer correction formula is derived which is shown to be substantially more accurate than previous approximations. Quantitative evaluation of the accuracy of this improved transducer correction is presented for simulated velocity measurements in a typical liquid and a typical solid specimen.