Systems and methods for measuring velocity with a radar altimeter are provided. In at least one embodiment a method for measuring velocity magnitude of a platform in relation to a surface comprises transmitting a radar beam, wherein the radar beam is aimed toward a surface; receiving a plurality of reflected signals, wherein the plurality of reflected signals correspond to portions of the transmitted radar beam that are reflected by a plurality of portions of the surface; and applying Doppler filtering to the plurality of signals to form at least one Doppler beam. The method also comprises identifying range measurements within each Doppler beam in the at least one Doppler beam; and calculating the velocity magnitude based on the range measurements of the at least one Doppler beam.