To distinguish Japanese single and geminate stops in two- and three-mora words spoken at varied speaking rates, the ratio of stop closure to the word in native speakers’ production was previously found to be a reliable measure. It was not clear, however, whether the stop closure relates more stably (1) to the entire “word” of any length than just (2) to the moras preceding and following the contrasting stops. This study examined this question with three- and four-mora nonsense words in Japanese. Results indicate that the stop closure duration relative to both of the units (1) and (2) were equally useful in accurately classifying single and geminate stops. This implies that the anchor to which the contrasting stop duration normalizes across rates does not have to be the entire “word” although the word is also a stable anchor.