A downhole pressure sensor to measure absolute pressure in an annulus and a method of measuring absolute pressure in an annulus are described. The sensor includes an inductor including primary windings and secondary windings, and a capacitor coupled to the secondary windings and disposed in the annulus, at least one of the plates of the capacitor being flexible. The sensor also includes a controller coupled to the primary windings, the controller introducing an input signal to the primary windings and receive a return signal from the primary windings, the return signal resulting from the input signal being transferred through the secondary windings to the capacitor and back through the secondary windings to the primary windings. The controller determines the absolute pressure from the return signal.