We present experimental results for adsorption of methane and ethane in activated carbon (AC610) and activated carbon fibers (KF1500 and A10) at pressures up to 10 MPa and temperatures between 313.15 and 373.15 K from a modified direct weighing densimeter. The general features of high-pressure adsorption in these carbons are discussed. We also report grand canonical Monte Carlo simulations and nonlocal density functional theory calculations to model methane adsorption in carbons. By combining these calculated results with the pore size distribution calculated-from previously obtained data, we are able to compare our simulation and theoretical results with those of our experiments.