Abstract: Systems and methods for calibrating calculations based on catheter-originated measurements. One embodiment comprises a method for calibrating volume calculations for a fluid-filled cavity, such as a heart chamber. In this method, a first catheter configured to measure electrical characteristics and a second catheter configured to measure geometric characteristics are inserted into a fluid-filled cavity. Electrical characteristics of the fluid-filled cavity are measured with the first catheter and geometric characteristics of the cavity are measured with the second catheter. A volume segment is determined based on the measured geometric characteristics of the cavity, and a corresponding volume segment is determined based on the measured electrical characteristics of the cavity.