Capacitor calibration in SAR converter. A method for calibrating a switched capacitor array in a SAR data converter is disclosed, which array includes a plurality of primary capacitors having a common node plate interfaced to a common node and a switched plate interfaced to a switch that is operable to be switched between first and second reference voltages. A comparator having an input connected to the common node and a reference input connected to a comparator reference node receives a comparator reference voltage. In a first calibration step for calibrating one of the primary capacitors, a reference capacitor is provided and then, the switched plate of the select primary capacitor is connected to the first reference voltage, the switched plate of the other capacitors and the reference capacitor are connected to the second reference voltage, and the common node and the comparator reference node are driven with a driver to dispose a first voltage thereon. In a second calibration step, the common node is allowed to float, the switched plate of the select primary capacitor is connected to the second reference voltage, the switched plate of the reference capacitor is connected to the first reference voltage, and the voltage on the common node is compared to the first voltage on the comparator reference node. A determination is then made as to whether the voltage on the common node is greater than the first voltage. A plurality of trim capacitors are provided and, if in the second calibration step, the voltage on the common node was determined to be greater than the first voltage, then one of the trim capacitors is disposed in parallel with the select one of the primary capacitors and then the first and second calibrating steps are repeated.