Hallo Jack,

at which frequency you wish to measure Xc? I ask, because many capacitor technologies suffer from big frequency dependence of capacitance. Also, some of them exhibit extreme temperature dependency and drift, so that a precision measurement of +-1% does not make much sense.
And finally, applied DC voltage can also have extreme influence on result of measurement.
Especially capacitors made of certain class II ceramics or aluminium electrolytic show such extreme difference, that it's hard to define their capacitance at all.

To sum up the above: Capacitance measured highly depends on applied methode!!! There are a lot of standards and first you should find out which standard has to be followed. An example:
Class II capacitors are often measured at 1kHz (sinus) with amplitude of 1V. Applied DC voltage is zero, ambient temperature is 25°C. Methode used is 'four gauge'.


Kai