Inter-ELM and ELM divertor heat loads were measured on JET in dedicated deuterium, hydrogen and helium discharges. Matched triplets (D, H, He) were obtained for different values of magnetic field, plasma current and heating power. In this article, the above experiments are described and the results are presented in terms of empirical scalings of inter-ELM and ELM wetted areas vs engineering parameters. The obtained inter-ELM scalings are then compared with those previously reported in the literature and with a wide range of theoretical predictions. Finally, implications for ITER are tentatively drawn, and a revised estimate for the power width in ITER is proposed.