The decline of central modal must and the increase in frequency of the semi-modals have (got) to, need (to), and want to is one of the most conspicuous grammatical changes that inner-circle varieties of English underwent in the second half of the 20th century. Such a replacement correlates with the increasing grammaticalization of the semi-modals in terms of semantic and quantitative developments. The current paper explores the differential grammaticalization of these items in four Asian varieties of English – those spoken in India, Hong Kong, Singapore, and the Philippines – with the aim of building a grammaticalization index that will allow to measure the extent to which the replacement of modal must with the semi-modals is completed in each of the varieties as compared to British English. After analyzing data from the private dialogue sections of the corresponding ICE corpora, Hong Kong English is shown to be the variety in which the replacement is closest to British English, followed by the Philippines, Singapore and India.