Lenition has been described in various ways but broadly involves multiple acoustic parameters. These include closure duration, VOT duration, periodicity, intensity, and absence of release burst. Because these concrete acoustic characteristics are variable and sometimes independent of one another, it is difficult to quantify the more abstract construct of lenition by referring to its separate components. This paper introduces a method of producing a quantitative measure of lenition, using a latent variable score derived via Principal Components Analysis on five individual parameters having a recognised relationship to consonant weakening.