We present a fast radio frequency-capacitance-voltage (RF-CV) method to measure the CV relation of an electronic device. The approach is more accurate, much faster, and more cost effective compared to the existing off-the-shelf solutions. Capacitances are determined using a single-frequency 1-port S-parameter setup constructed from discrete components. We introduce a new way to correct for nonlinearities of the used components, which greatly increases the accuracy with which the phase and magnitude of the reflected signal is measured. The measurement technique is validated on an RF microelectromechanical systems capacitive switch and a barium-strontium-titanate tunable capacitor. Complete CV curves are measured in less than a millisecond, with a measurement accuracy well below 1%.