Although classical density functional theory provides reliable predictions for the staticproperties of simple equilibrium fluids under confinement, a theory of comparative accuracyfor the transport coefficients has yet to emerge. Nonetheless, there is evidence thatknowledge of how confinement modifies static behavior can aid in forecasting dynamics.Specifically, recent molecular simulation studies have shown that the relationship betweenexcess entropy and self-diffusivity of a bulk equilibrium fluid changes only modestly whenthe fluid is isothermally confined, indicating that knowledge of the former might allowsemi-quantitative predictions of the latter. Do other static measures, such as those thatcharacterize free or available volume, also strongly correlate with single-particle dynamicsof confined fluids? Here, we investigate this question for both the single-componenthard-sphere fluid and hard-sphere mixtures. Specifically, we use molecular simulationsand fundamental measure theory to study these systems at approximately103 equilibrium state points. We examine three different confining geometries (slit pore, squarechannel, and cylindrical pore) and the effects of particle packing fraction andparticle–boundary interactions. Although average density fails to predict some keyqualitative trends for the self-diffusivity of confined fluids, we provide strong empiricalevidence that a new generalized measure of available volume for inhomogeneous fluidscorrelates excellently with self-diffusivity across a wide parameter space in these systems,approximately independently of the degree of confinement. An important consequence,which we demonstrate here, is that density functional theory predictions of thisstatic property can be used together with knowledge of bulk fluid behavior tosemi-quantitatively estimate the self-diffusion coefficient of confined fluids underequilibrium conditions.