We have used direct, low-frequency scanning capacitance microscopy measurements to characterize variations in thin, dielectric films with up to 1 nm thickness and ∼200 nm lateral resolution. This technique may be used on metallic as well as semiconducting substrates because it does not rely upon d C/d V measurements. We also find that the sensitivity of capacitance to film thickness can be enhanced by an aqueous meniscus that typically forms between the atomic force microscope tip and the sample surface. Further, we quantified the nanometre-scale capacitance of the tip–meniscus–sample system that is sensitive to variations in film thickness by making simultaneous capacitance and cantilever deflection measurements. This capacitance is used along with an average film thickness to quantify variations in film thickness.