Given an unsatisfiable k -CNF formula we consider two complexity measures in Resolution: width and total space. The width is the minimal W such that there exists a Resolution refutation of with clauses of at most W literals. The total space is the minimal size T of a memory used to write down a Resolution refutation of , where the size of the memory is measured as the total number of literals it can contain. We prove that T = (( W − k ) 2 ) .