With 2015 marking the end of the era for the millennium development goals (MDG) and the start of that for sustainable development goals (SDG), with reduction of global poverty featuring prominently in both sets of goals, there has recently been a surge of studies that seek to quantify the magnitude of global poverty. Examples include Cruz et al. (2015), Ferreira et al. (2016), Jolliffe and Prydz (2015), Kakwani and Son (2016). The literature on estimating global poverty[1] can be traced back to Ahluwalia et al. (1979) with the next major contribution by Ravallion et al. (1991). In the nearly 4 decades that have elapsed since the Ahluwalia et al. (1979) study, the complexity of the exercise has grown many fold with an increase in the number of countries included in the poverty enumeration. The complexity has been reflected in changes in the manner the “international poverty line” (IPL) has been defined and implemented in successive poverty counts. While the Ahluwalia et al. (1979) study was based on the Indian poverty line used as the IPL, Ravallion et al. (1991) provided the first dollar-a-day poverty line at 1985 PPPs. This study, which was designed to answer a set of poverty related questions on world poverty and give aggregate results for 86 countries in the mid-1990s, was conducted as a background paper for the World Development Report, 1990. Since this was the first time the concept of an “international poverty line” was proposed and implemented, let us explain how the $1 a day figure was arrived at. Ravallion et al. (1991) proposed measuring global poverty by the standards of the poorest countries, based on a survey of national poverty lines. Drawing on 33 national poverty lines for the 1970s and 1980s (for both developed and developing economies), Ravallion et al. (1991) proposed a line of $23 a month ($0.76 a day) at 1985 consumption PPP. That value was the predicted poverty line for the poorest country in the sample of 88 countries (Somalia), based on a regression model that ran a semi-log regression of the national poverty line on per capita mean consumption and per capita mean consumption square (all at 1985 PPP). This value was quite close to the poverty line of India. As Ravallion et al. (1991, pp. 348/349) note: Thus, India’s poverty line is very close to the poverty line we would predict for the poorest country, and as such, can be considered a reasonable lower bound to the range of admissible poverty lines for the developing world […]. A more generous, and more representative, absolute poverty line for low-income countries is $31, which (to the nearest dollar) is shared by six of the countries in our sample, namely Indonesia, Bangladesh, Nepal, Kenya, Tanzania, and Morocco, and two other countries are close to this figure (Philippines and Pakistan). We shall use both these poverty lines, interpreting the lower line as defining “extreme absolute poverty”.