Recent infra-red measurements of divertor power loads on JET and AUG [1], revealed that the inter-ELM power width at the outer mid-plane in attached ELMy H-modes does not exhibit any noticeable scaling with machine size [1]. Making use of these results to calculate the effective radial heat diffusivity, and then including this in parametrized expressions based on edge plasma fluid simulations, it is possible to estimate the peak inter-ELM divertor power loads in future fusion devices with conventional divertor designs.