An example device for coding video data includes a memory configured to store video data, and one or more processors implemented in circuitry and configured to code a first motion vector difference (MVD) representing a difference between a first motion vector of a current block of video data predicted using affine prediction and a first motion vector predictor (MVP) for the first motion vector, predict a second MVD from the first MVD for a second motion vector of the current block, and code the current block using affine prediction according to the first motion vector and the second motion vector. Predicting the second MVD from the first MVD in this may reduce bitrate of a bitstream including coded video data, as well as improve processing efficiency.