Thanks for your question. Poverty lines are calculated by assessing the cost of a basic consumption basket for each member of a household, usually based on calorific intake needs. There are different ways of doing this, some that assume that children need less calories than adults, some that treat adults and children as equal in this respect. The NBS approach that leads to the 64% number uses the second approach, also known as the "per capita" method. The poverty headcount rate is then the percentage of the population with reported consumption in the survey less than the poverty line calculated in this way.