The plane‐wave reflection coefficient for a continuously stratified fluid sediment can be simply calculated by representing the sediment as a stack of thin homogeneous layers. The error in such an approximation is usually estimated by increasing the number of layers and comparing the result with the original calculation. This kind of iterative approach can be both time consuming and frustrating. In this paper, the distorted‐wave Born approximation (DWBA) is used to derive a formula for the error associated with a single thin layer (local error) as well as for the total or global error. The local error formula can be used to devise a reasonablea priorilayering scheme for any continuous fluid sediment. The global error formula then allows an accurate estimate of the total error to be calculated at the same time as the reflection coefficient. Numerical results are presented for the case where the square of the wave number varies linearly with depth. The DWBA formula is shown to give an excellent estimate of the actual global error. [Work supported by Naval Electronic Systems Command.]