The flowmeter is basically a curved rotameter, having a tapered conduit which is curved in the vertical plane. Inlet and outlet plenum chambers are provided for passing the fluid through the curved rotameter. A ball is positioned within the curved rotameter so that it can move up the conduit under the influence of the stream of fluid. A differential pressure sensor (which may be mounted on a partition separating the plenum chambers) determines the pressure differential between both sides of the ball. This pressure differential is an indication of the rate of flow of fluid through the meter. In a preferred embodiment, two conduits with opposed curves are used to compensate for variations in vertical alignment of the flowmeter.