Apparatus and associated methods relate to measuring density of aircraft fuel. The aircraft fuel is circumferentially pumped about an impeller axis by a centrifugal pump. Differential pressure of the aircraft fuel is measured between two different points within the centrifugal pump, each a different radial distance from an impeller axis. Rotational frequency of the impeller of the centrifugal pump is measured. Density of the aircraft fuel is calculated based on the rotational frequency and the differential pressure.