a liquid density measurement system comprises a capacitance probe and a temperature sensor both immersible in a liquid the density of which is to be measured . signals derived from the probe and sensor are converted into respective electrical signals representing changes in the dielectric constant and temperature of the liquid respectively . these signals are scaled in a predetermined mutual ratio and then summated to give an output signal proportional to the density of the liquid . the scaling ratio is set according to predetermined liquid parameters such that the accuracy of the density represented by the output signal is unaffected by changes in liquid composition .