The pounds to kg converter calculator tool speed up the computation and displays the result in a fraction of a second. Visit 128 Kilograms to Pounds Conversion Pounds : The pound or pound-mass (abbreviations: lb, lbm, lbm, ℔[1]) is a unit of mass with several definitions. Nowadays, the most common is the international avoirdupois pound which is legally defined as exactly 0.45359237 kilograms.