Thermally coupled distillation is well-proven in low temperature gas processing where energy is relatively expensive. Although the thermodynamic efficiency of thermally coupled columns is similar to conventional columns, thermal coupling reduces energy flows. This can lead to attractive savings in both energy and capital cost. This paper shows that the conventional Fenske-Underwood-Gilliland method for short cut distillation design is as appropriate for thermally coupled columns as it is for conventional distillation. This enables comparisons of conventional and thermally coupled columns to be made easily, and should help to make thermal coupling a more accepted means of improving energy efficiency in distillation systems.