What is the length of a knot in a polymer?

We give statistical definitions of the length, 1, of a loose prime knot tied into a long, fluctuating ring macromolecule. Monte Carlo results for the equilibrium, good solvent regime show that (1) similar to N-t, where N is the ring length and t similar or equal to 0.75 is independent of the knot type. In the collapsed regime below the theta temperature, length determinations based on the entropic competition of different knots within the same ring show knot delocalization (t similar or equal to 1).