Based on first-principles electronic structure calculations, we have derived an efficient physical descriptor for the ion mobility in battery electrodes and solid electrolytes which is a critical performance parameter in electrochemical energy storage and conversion. This descriptor is entirely composed of observables that are easily accessible: ionic radii, oxidation states and the difference in the Pauling electronegativities of the involved species. Within a particular class of materials, the activation barriers for migration are connected to this migration parameter through linear scaling relations both as far as the variation of the cation chemistry of the charge carriers and the anion chemistry of the host lattice are concerned. The validity of these scaling relations indicates that a purely ionic view of ion mobility in solids falls short of capturing all factors influencing this mobility. The identification of these scaling relations has the potential to significantly accelerate the discovery of materials with desired mobility properties.