AbstractThe retention times (t R) of n‐alkanes (C16–C22) eluted from capillary columns of different diameters are accurately predicted by using the equation proposed by Krisnangkura et al. (J. Chromatogr. Sci. 1997, 35, 329–332). The numerical values of four thermodynamically related constants (a, b, c, and d) of the BP‐1 (100% dimethylpolysiloxane) capillary column (0.32 mm ID×25 m, film thickness, 0.25 μm) are –6.169, –0.512, 226.98, and 410.30, respectively. For columns of the same stationary phase but of different inside diameters and film thickness, accurate tR values can be predicted by using the same numerical values of the last three constants but the first constant (a) is changed by the difference in the natural logarithm of the column phase ratios (β). All the derived numerical values of each column were tested with FAMEs and with n‐alkanes in temperature‐programmed GC (TPGC). All the predicted tR values agree well with the experimental values. About 77% of the TPGC data have errors lower than 0.5% and the largest value is –1.04%.