Abstract: An example of an apparatus is provided. The apparatus includes a container to store a powder. The apparatus includes a flow generator to move a gas to the container. The flow generator is to move the gas at a first velocity and a second velocity, the first velocity to fluidize the powder in a fluidized state, and the second velocity to pass through stationary powder in a powder pack. The apparatus includes pressure sensors to measure pressures in the container. The apparatus includes a measurement engine in communication with the pressure sensors, wherein the measurement engine is to calculate a mass of the powder based on a fluidized pressure differential and based on a pack pressure differential.