Ion densities, electron temperatures, plasma potentials, and absorbed powers are measured in a planar inductively coupled argon plasma source at different input powers, pressures, and aspect ratios (radius/length) and are compared to both a global (volume-averaged) model and a two-dimensional (2D) fluid model. Qualitatively, the trends between the models and experiment are similar. Radial ion density profiles at different aspect ratios and pressures are also measured. An ion density peak off-axis is measured at a high aspect ratio and predicted by the 2D fluid model.