The poverty line is estimated in India based on how much it would cost someone to buy enough calories (food) required to sustain themselves. This is according to the government 2400 and 2100 calories in rural and urban areas respectively. The figure was first calculated in 1978 and was then Rs.61.80 for rural and Rs.71.30 for urban areas. Since then the figure has been at various points been revised or adjusted for inflation. A point to be noted is that the food prices in rural areas are obviously lower than urban areas, so separate prices are calculated for both categories.