Standard Italian is canonically described as a language that displays a phonological length contrast in the consonant system, but no corresponding contrast in the vowel system. Despite this fact, it is widely accepted that Italian vowels are phonetically lengthened by speakers in open stressed syllables, especially penultimate ones. However, no studies on the perception of both vowel and consonant length have been conducted. A crucial question remains open: do Italian listeners perceive the durational cues underlying a hypothesized phonological length contrast (for consonants) and a hypothesized phonetic contrast (for lengthened vowels) differently? We investigated this question in an online AX perception experiment with over a hundred Italian listeners. Results from a Mixed Effect Logistic regression model and Machine Learning classification showed that Italian listeners displayed indistinguishable identification functions for both the phonological length contrast of consonants and the “putative” phonetic durational contrast of vowels, meaning that perceptual discrimination of segmental duration was similar for phonologically long and short consonants and for vowels that were “phonetically” lengthened (or shortened) in open penultimate syllables. These results suggest therefore that Italian listeners discriminate differences in duration similarly for both consonants and vowels, either as a cue to phonological length contrasts or stress or both.