A method for measuring three-dimensional gate dielectric structures can involve forming test patterns that cover a range of dimensional values for the fins on which the gate dielectric structures are formed. Then, by measuring the gate dielectric properties and then correlating those measurements with the underlying fin dimensions, a relationship between fin dimension(s) and gate dielectric properties can be determined. That relationship can then be applied to actual device structures to interpolate/extrapolate gate dielectric property values based on the fin dimensions in the actual device.