A processor includes a core to execute an instruction for conversion between an element array and a packed bit array. The core includes logic to identify one or more bit-field lengths to be used by the packed bit array, identify a width of elements of the element array, and simultaneously for elements of the element array and for bit-fields of the packed bit array, convert between the element array and the packed bit array based upon the bit-field length and the width of elements of the element array.