We examine the operational state complexity assuming that the operands of a regular operation are represented by nondeterministic finite automata, while the language resulting from the operation is required to be represented by a deterministic finite automaton. We get tight upper bounds 2 n for complementation, reversal, and star, 2 m for left and right quotient, 2 m+n for union and symmetric difference, 2 m+n − 2 m − 2 n + 2 for intersection, 2 m+n − 2 n + 1 for difference, 3 4 2 m+n for concatenation, and 2 mn for shuffle. We use a binary alphabet to describe witnesses for complementation, reversal, star, and left and right quotient, and a quaternary alphabet otherwise. Whenever we use a binary alphabet, it is always optimal.