For convolutional codes, thc variation of the minimum distance between nonmerging codewords with the lengths of those codewords is considered for all finite lengths. This is carried out in terms of a new distance parameter for convolutional codes do, the minimum average weight per branch over all cycles. Upper and lower bounds on do for binary convolutional codes of rate

are presented. The tradeoff between

and the free distance

is obtained for small memory length codes.