Systems, apparatuses, and methods related to bit string compression are described. A method for bit string compression can include determining that a particular operation is to be performed using a bit string formatted according to a universal number format or a posit format to alter a bit width associated with the bit string from a first bit width to a second bit width and performing a compression operation on a bit string formatted according to a universal number format or a posit format to alter a bit width associated with the bit string from a first bit width to a second bit width. The method can further include writing the bit string having the second bit width to a first register, performing an arithmetic operation or a logical operation, or both using the bit string having the second bit string width, and monitoring a quantity of bits of a result of the operation.