Examples herein relate to convolution accelerators. An example convolution accelerator may include a transformation crossbar array programmed to calculate a Fourier Transformation of a first vector with a transformation matrix and a Fourier Transformation of a second vector with the transformation matrix. A circuit of the example convolution accelerator may multiply the Fourier Transformation of the first vector with the Fourier Transformation of the second vector to calculate a product vector. The example convolution accelerator may have an inverse transformation crossbar array programmed to calculate an Inverse Fourier Transformation of the product vector according to an inverse transformation matrix.