A correlation between characteristic reaction zone widths, calculated from detailed chemical kinetic models, and experimentally measured or numerically simulated detonation cell sizes is analyzed. An approach is proposed to generalize such a correlation, taking into account the multidimensional structure of real detonations. It is based on the characteristic reaction zone width, delta, calculated at initial conditions that are representative for a multidimensional detonation wave. The ratio, A, of the detonation cell width, lambda, to the characteristic reaction zone width delta is considered to be a function of two stability parameters (dimensionless effective activation energy and a parameter describing the relation between chemical energy and initial thermal energy of the combustible mixture). This approach is evaluated against experimental data and results of multidimensional calculations. The resulting semi-empirical correlation is suggested to describe the dependence of the lambda/delta-ratio on the stability parameters. This gives a basis for the prediction of detonation cell widths from detailed chemical kinetic calculations over a wide range of mixture compositions and initial conditions.